r      B  CKKCLBY 

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UNIVERSITY  OF 
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GIFT   OF 
C.      L.    Camp 


The  Anatomy 

of  the 

Domestic  Fowl 


B.  F.  Kaupp,  M.  S.,  D.  V.  M. 

Poultry  Investigator  and  Pathologist  in  the   North  Carolina 

Experiment  Station,  State  Department  of  Agriculture,  and  the 

State  College  of  Agriculture;  Formerly  Director  of  Anatomy 

Laboratory,  Kansas  City  Veterinary  College 


Illustrated 


Philadelphia  and  London 

W.  B.  Saimders  Company 

1918 


Copyright,  1918,  by  W.  B.  Saunders  Company 


«^>V2s^rv^ 


PRINTED    IN    AMERICA 


To 

'DAN  T.  GRAY,  B.  s.,  A.  B.,  M.  s. 

CHIEF,  ANIMAL  INDUSTRY  DIVISION,  NORTH  CAROLINA 

EXPERIMENT  STATION 

As  A  TOKEN  OF  RESPECT  AND  GRATITUDE  THIS 
VOLUME  is  DEDICATED 

BY 
THE  AUTHOR 


M  27X2 


FOREWORD 


ADVANCED  work  in  the  study  of  poultry  husbandry  is  now  being 
done  in  this  country,  to  a  greater  or  less  extent,  at  all  the  two  score 
and  more  Agricultural  and  other  Colleges  and  Experiment  Stations. 
From  these  institutions  comes  the  demand  for  a  text-book  on  the 
Anatomy  of  the  Domestic  Fowl.  No  complete  text-book  on  the 
subject,  up  to  the  present,  has  existed.  It  is  with  the  hope  of 
meeting  the  demand  that  this  book  is  published. 

In  supplementing  the  information  gathered  from  the  books  and 
articles  listed  in  the  bibliography,  the  author  has  spent  much  time 
and  effort  in  obtaining  the  matter  here  presented.  As  this,  however, 
is  the  initial  complete  text  on  the  subject  necessarily  much  remains 
to  be  added  and  corrected.  The  author  would  welcome  suggestions 
and  corrections  from  any  one  into  whose  hands  the  book  may  come. 

B.  F.  KAUPP. 

THE  NORTH  CAROLINA  STATE  COLLEGE  OF  AGRICULTURE, 
WEST  RALEIGH,  NORTH  CAROLINA, 
September,  1918. 


CONTENTS 


OSTEOLOGY 

PAGE 

OSSEOUS  STRUCTURE 17 

CLASSIFICATION  OF  BONES 20 

COMPOSITION  OF  BONE • 21 

SKELETON  OF  THE  FOWL : 21 

Axial  Skeleton .' 23 

Cranium  and  Face 23 

Occipital 25 

Ethmoid 27 

Sphenoid 28 

Frontal ' .    .  ' 29 

Parietal 29 

Temporal 29 

Premaxilla 31 

Maxilla      32 

Nasal 32 

Lacrimal 32 

Palatine 33 

Pterygoid 33 

Zygomatic 33 

Vomer 33 

Jugal  and  Quadratojugal 33 

Quadrate 34 

Inferior  Maxilla ' 34 

Turbinate  Bones 34 

Hyoid 35 

Vertebral  Column 35 

Cervical  Vertebrae 35 

Atlas 37 

Axis 37 

Dorsal  Vertebrae 39 

Lumbosacral  Vertebrre 39 

Coccygeal  Vertebrae 41 

Ribs 41 

Sternum - 42 

Appendicular  Skeleton 43 

Shoulder  Girdle 43 

Fore  Limb.    .    . 44 

Pelvic  Girdle 48 

Hind  Limb 50 

ARTHROLOGY 

KINDS  OF  JOINTS 56 

MOVEMENTS  OF  JOINTS 56 

LlGAMENTOUS  STRUCTURE  .    . 57 

II 


12  CONTENTS 

PAGE 
LIGAMENTS  OF: 

Ear 58 

Jaw 58 

Vertebrae 58 

Ribs 59 

Sternum 59 

Shoulder-joint 61 

Elbow-joint 61 

Carpal  Joint 62 

Finger 64 

Pelvis 65 

Hip-joint 65 

Knee-joint 65 

Tibiometatarsal  Joint 69 

Toes 69 

MYOLOGY 

KINDS  AND  STRUCTURE  OF  MUSCLES 70 

FASCIA 71 

MUSCULAR  NOMENCLATURE 71 

True  Dermal  Muscles 71 

Dermo-osseous  Muscles 73 

Muscles  of  the  Head 76 

Muscles  of  the  Tongue 79 

Cervical  Muscles 81 

Muscles  of  the  Air  Passages 86 

Superior  Larynx 86 

Inferior  Larynx 86 

Sternal  Muscles 90 

Abdominal  Muscles 90 

Dorsolumbar  Muscles , 92 

Coccygeal  Muscles 93 

Costal  Muscles 96 

Anterior  Pectoral  Muscles 99 

Pectoral  Muscles 100 

Muscles  of  the  Scapular  Region  ....        101 

Muscles  of  the  Brachial  Region 104 

Muscles  of  the  Forearm  and  Hand 105 

Digital  Muscles • 109 

Muscles  of  the  Posterior  Limb in 

Tibial  Group  of  Muscles 117 

Muscles  of  the  Eye 1 24 

Muscles  of  the  Ear 128 

FUNCTIONS  OF  MUSCLES 128 

SPLANCHNOLOGY 

DIGESTIVE  APPARATUS 135 

Mouth 135 

Tongue 139 

Pharynx 141 

Glands  Adjacent  to  Mouth  and  Pharynx 141 

Esophagus 142 

Crop 142 

Stomach 143 

Proventriculus 143 

Gizzard 145 

Small  Intestine 147 


CONTENTS  13 

PAGE 

Large  Intestine 150 

Caeca 151 

Cloaca 151 

COURSE  OF  THE  FOOD 152 

ACCESSORY  ORGANS  OF  DIGESTION ~- r-*£2- 

Liver 153 

Pancreas 155 

Spleen 155 

ABDOMINAL  AND  PELVIC  CAVITIES 156 

PERITONEUM  AND  MESENTERY 156 

RELATIONS  OF  THE  VISCERAL  ORGANS  OF  THE  DOMESTIC  FOWL 158 

RELATIONS  OF  THE  VISCERAL  ORGANS  OF  THE  BABY  CHICK 165 

UROGENITAL  SYSTEM 169 

Urinary  Apparatus 169 

Kidneys 169 

Ureter 174 

Male  Generative  Organs 175 

Testicles 175 

Vas  Deferens 178 

Female  Generative  Organs 178 

Egg 180 

Oviduct 182 

Parts  of  the  Oviduct 183 

Ligaments  of  the  Oviduct 188 

DUCTLESS  GLANDS , 190 

Thyroid  Gland. 190 

Thymus  Gland 190 

Adrenal  Gland 191 

RESPIRATORY  APPARATUS 193 

Nostrils  and  Nasal  Chambers   .    .  , 193 

Pharynx  and  Superior  Larynx 193 

Trachea 194 

Inferior  Larynx ....  194 

Bronchi  and  the  Lungs 195 

Air-sacs 199 

ANGIOLOGY 

CIRCULATORY  APPARATUS 206 

Heart 206 

Structure  of  the  Heart ' 207 

Blood-vessels 209 

Structure  of  the  Capillaries  and  Arteries 209 

Structure  of  the  Veins 211 

Arterial  Trunks 211 

Branches  of: 

Arteria  Brachiocephalica 213 

Arteria  Carotis  Cerebralis  Interna 214 

Arteria  Carotis  Externa 214 

Arteria  Carotis  Facialis 214 

Aorta  Posterior : 224 

Venous  Trunks 233 

Branches  of: 

Venae  Cavae  Anteriores 234 

Vena  Jugularis 237 

Vena  Occipitalis  Externa 239 

Venous  Sinuses  of  the  Head 239 

Veins  of  the  Brain  Cavity 241 

Veins  of  the  Neck 242 


14  CONTENTS 

PAGE 

Branches  of  the  Vena  Subclavia 243 

Veins  of  the  Dorsal  Region 243 

Veins  of  the  Thorax 244 

Veins  of  the  Fore  Limb 245 

Branches  of  the  Iliaca .  246 

Branches  of  the  Vena  Iliaca  Interna 247 

Posterior  Vena  Cava 247 

Veins  of  the  Posterior  Extremity 248 

Branches  of  the  Vena  Cava  Posterior      . 248 

Veins  of  the  Caudal  Region  and  Pelvic  Cavity 250 

Veins  of  the  Truncus  Vena  Iliaca  Communis 252 

Visceral  Veins  of  the  Posterior  Vena  Cava 252 

Lymphatic  System 254 

BLOOD  AND  ITS  FUNCTIONS 257 

FATE  OF  THE  ERYTHROCYTE 261 

NEUROLOGY 

NERVOUS  SYSTEM 264 

Cranial  Nerves 265 

Olfactorius 265 

Opticus . 267 

Motoris  Oculi 267 

Patheticus 268 

Trifacialis 268 

Abducentes 270 

Facialis  and  Acousticus  .    .    . 271 

Vagus  Group 272 

Glossopharyngeus 272 

Vagus  or  Pneumogastricus 273 

Accessorius  Spinalis 274 

Hypoglossus 274 

SpinalCord 275 

Structure  of  the  Cord 275 

Structure  of  the  Nerve  Trunks  and  Ganglia 277 

Spinal  Nerves 281 

Brachial  Plexus : 282 

Lumbosacral  or  Crural  Plexus 285 

Brain 288 

Coverings  of  the  Brain 288 

Structure  of  the  Brain ' 289 

Divisions  of  the  Brain 290 

Sympathetic  Nervous  System 297 

Functions  of  the  Nervous  System 300 

ESTHESIOLOGY 

Sense  Organs 303 

Sight 303 

Hearing 305 

Smell 307 

Taste 307 

Touch 307 

STRUCTURE  OF  APPENDAGES 309 

EMBRYOLOGY 

SPERMATOGENESIS .  318 

OOGENESIS 319 


CONTENTS  15 

PAGE 

FERTILIZATION 319 

OUTLINE  FOR  LABORATORY  STUDY  OF  THE  CHICK .  330 

Living  Embryo 330 

Preparation  for  Study  of  Entire  Embryos  and  Sections 330 

Points  to  be  Observed  in  the  Study 332 

DERIVATIVES  or  THE  GERM-LAYERS 342 

PREPARATION  OF  STRUCTURES  FOR  STUDY 343 

Directions  for  Dissecting  Muscles 343 

Directions  for  Study  of  the  Viscera 344 

Directions  for  Study  of  the  Arteries 345 

Study  of  the  Structure  of  Bones 346 

Special  Technic  for  Dissection  of  Cranial  and  Spinal  Nerves 347 

Directions  for  Study  of  Soft  Structures 347 

To  Stain  Sections  of  Liver  for  Study  of  Kupffer  Cells 349 

To  Prepare  Anatomical  Specimens  for  Museum 349 

To  Make  Specimens  Transparent 350 

EQUIPMENT  FOR  THE  DISSECTION  LABORATORY 351 

BIBLIOGRAPHY  .    .    . 353 

INDEX 355 


ANATOMY 

OF  THE 

DOMESTIC  FOWL 


OSTEOLOGY 


Osseous  Structure. — Bone  is  structurally  modified  connective 
tissue  which  has  become  hard  by  being  impregnated  with  calcium 
salts. 

Kinds  of  Bone  Tissue. — There  are  two  kinds  of  bone  tissue: 
substantia  compacta,  or  compact  bone  tissue;  and  substantia  spon- 
giosa,  or  spongy,  cancellous  bone  tissue. 

Compact  Bone  Tissue. — The  compact  bone  tissue  forms  the  hard 
outer  layer  of  all  bones.  It  is  thickest  in  the  shaft  and  becomes  thin 
toward  the  extremities.  Through  the  compact  bone  tissue  approxi- 
mately parallel  with  the  longitudinal  axis  of  the  bone,  run  canals 
called  Haversian  canals,  through  which  pass  blood  and  lymph  ves- 
sels for  the  nourishment  of  the  bone  and  nerves.  The  Haversian 
canals  are  surrounded  by  concentric  lamellae.  The  spaces  between 
the  cylinders  thus  formed  are  filled  with  interstitial  lamella;  and 
both  the  exterior  surface  of  the  bone  and  the  interior  surface  sur- 
rounding the  medullary  canal,  are  built  up  of  peripheral,  or  circum- 
ferential lamellae.  Between  the  lamellae,  somewhat  irregularly 
placed,  are  minute  reservoirs,  called  lacuna,  which  contain  bone 
corpuscles.  From  the  lacunae  radiate  minute  canals,  or  canali- 
culi,  which  maintain  circulation  through  the  bone  substance,  and 
which  communicate  with  the  Haversian  canals.  Complex  anasto- 
moses exist  among  the  canaliculi.  Still  other  channels  for  the  pas- 
sage of  blood-vessels  are  Volkmann's  canals  which  pierce  the  periph- 
eral lamellae,  thus  allowing  vessels  to  pass  from  the  periosteum  to 
the  Haversian  canals.  Similar  channels  afford  communication 
between  the  inner  Haversian  canals  and  the  medullary  cavity. 

The  entire  structure  composed  of  an  Haversian  canal,  its  sur- 
2  17 


1 8  ANATOMY   OF   THE   DOMESTIC   FOWL 

rounding  lamellae,  lacunae,  and   canaliculi,    with    their   contained 
vessels,  is  called  an  Haversian  system. 

Cancellous  Bone  Tissue. — The  cancellous  bone  tissue  forms  the 
bulk  of  the  short,  flat,  and  irregular  bones  and  of  the  extremities 
of  the  long  bones.  It  consists  of  delicate  bony  plates  and  spicules, 
which  intercross  in  various  directions.  The  spaces  between',  these 
plates  and  spicules,  called  cancelli,  are  occupied  by  marrow  except  in 
the  bones  that  are  pneumatic.  The  blood-vessels,  lymphatics,  and 
nerves  course  through  this  marrow  but  are  not  arranged  in  an  Ha- 
versian system. 


PIG.   i. — Longitudinal  section  of  compact  bone  of  the  femur  of  the  hen.     I, 
Haversian  canals.     2,  Lacunae  with  their  canaliculi. 

The  Periosteum. — Covering  the  surface  of  bone,  except  at  the 
articular  surface  where  it  is  covered  with  cartilage,  is  a  membrane, 
the  periosteum,  which  consists  of  two  layers:  an  outer,  fibrous, 
protective  layer,  and  an  inner,  cellular,  osteogenic  layer.  The  outer 
layer  consists  principally  of  white  fibrous  tissue.  The  inner  layer 
contains  many  more  connective-tissue  cells,  which  gradually  be- 
come more  closely  aggregated  as  we  proceed  toward  the  osseous 
surface;  but  there  is  no  sharply  defined  line  of  demarcation  between 
the  two  periosteal  layers. 


OSTEOLOGY 


\ 


FIG.  2. — Transverse  section  of  compact  bone  of  the  femur  of  the  hen.     I.  The 
lacunae  and  canaliculi.     2,  The  periosteum. 


PIG.   3. — Transverse  section  of  compact  bone  of  the  femur  of  the  hen  showing 
the  lacunae  and  canaliculi  under  high  magnification 


2O  ANATOMY   OF   THE   DOMESTIC   FOWL 

The  periosteum  is  firmly  attached  to  the  bone  by  trabeculae  of 
fibrous  tissue,  called  the  fibers  of  Sharpey.  These  fibers  of  Sharpey 
penetrate  the  bone  at  right  angles  to  its  surface  and  carry  blood- 
vessels. 

Marrow. — There  are  two  kinds  of  marrow:  yellow,  or  medulla 
ossium  flava,  and  red,  or  medulla  ossium  rubra. 

The  yellow  marrow  occurs  in  all  bones  except  the  femur  and  proxi- 
mal portion  of  the  tibia  of  adult  fowls.  It  is  composed  of  a  network 
of  fibrous  tissue  carrying  blood-vessels,  fat  cells,  and  myelocytes,  or 
marrow  cells. 

The  red  marrow  is  found  throughout  the  femur  and  the  proximal 
portion  of  the  tibia,  and  in  a  few  of  the  pelvic  bones  and  vertebrae 
in  the  adult  fowl,  and  in  certain  other  bones  of  the  baby  chick. 
Red  marrow  consists  of  a  delicate  network  of  connective  tissue 
supporting  a  dense  capillary  plexus,  a  small  amount  of  fat,  and 
numerous  cells.  The  cellular  elements  of  red  marrow  consist  of 
marrow  cells  which  contain  large  nuclei  and  possess  ameboid  move- 
ment, red  blood  cells,  giant  cells  containing  one  or  more  nuclei,  and 
various  kinds  of  leucocytes,  including  eosinophiles,  mast  cells,  and 
also  osteoclasts. 

Growth  of  Bone. — In  the  baby  chick,  only  the  shaft  and  a  portion 
of  the  extremities  of  the  long  bones  are  thoroughly  ossified,  the  ex- 
treme ends,  and  of  the  femur  most  of  the  articular  head,  being 
cartilaginous.  The  bones  grow  in  length  by  an  increase  in  the  carti- 
lage, the  cartilage  gradually  becoming  ossified.  Growth  in  diameter 
is  accomplished  by  the  constant  deposition  of  new  "layers  of  bone 
beneath  the  periosteum.  During  this  process  the  osteoclasts  ab- 
sorb the  bone  from  within.  The  formation  of  the  marrow  cavity  is 
thus  effected. 

Classification  of  Bones. — The  bones  of  the  fowl  are  classified 
as  long,  short,  flat,  and  irregular. 

Long  Bones. — The  long  bones  occur  in  the  legs  and  wings,  where 
they  serve  as  levers  to  sustain  weight  and  make  locomotion  possible. 
A  long  bone  consists  of  a  shaft  and  two  extremities.  The  superior 
is  called  the  proximal  and  the  inferior  the  distal  extremity.  The 
expanded  articular  surfaces  in  forming  joints  with  adjoining  bones 
afford  ample  space  for  the  attachment  of  ligaments.  The  shaft  is 
cylindrical  and  hollow. 

Short  Bones. — Short  bones  occur  in  the  feet  and  in  the  wings. 
Their  structure  is  similar  to  that  of  the  long  bones. 


OSTEOLOGY  21 

Flat  Bones. — The  flat  bones  occur  where  extensive  protection 
is  needed,  as  in  the  cranial  region;  or  where  large  surface  for  muscular 
attachments  is  needed,  as  in  the  costal  and  pelvic  regions.  Flat 
bones  are  made  up  of  two  thin  layers  of  compact  bone  with  a  vari- 
able amount  of  cancellous  tissue  interposed. 

Irregular  Bones. — The  irregular  bones  include  the  vertebrae, 
the  patellae,  and  the  carpal  bones. 

Composition  of  Bone. — Bone  consists  of  organic  and  inorganic 
matter.  Organic  matter  gives  toughness  and  elasticity  to  the  bone, 
and  inorganic  matter  hardness.  The  organic  substance  of  bone  is 
called  ossein.  When  boiled  in  water  ossein  is  resolved  into  gelatin. 
The  following  tables1  give  the  results  of  an  analysis  of  the  femur, 
fresh,  of  a  mature  hen. 

Fresh  femur: 

Water 18. 23  per  cent. 

Dry  matter 81 . 77  per  cent. 

Dry  matter: 

Organic  matter. 63 .09  parts 

Inorganic  matter 18 . 68  parts 

Salts  in  dry  matter: 

Calcium 6 . 970  per  cent. 

Magnesium o. 283  per  cent. 

Potassium o .  004  per  cent. 

Sodium 0.276  per  cent. 

Iron o .  020  per  cent. 

Phosphorus 3 . 210  per  cent. 

Sulphur '. 0.085  Per  cent. 

Chlorine 0.520  per  cent. 

Carbon  dioxid o. 550  per  cent. 

The  inorganic  matter  of  the  femur  of  the  hen  consists  of  18.68 
parts  or  22.84  per  cent,  of  dry  matter,  and  the  organic  matter  of 
77.16  per  cent.  Stated  in  other  words  the  femur,  including  its 
contained  marrow,  consists  of  organic  and  inorganic  matter  in  the 
ratio  of  3.4,  approximately,  to  i. 

The  Skeleton  of  the  Fowl. — The  skeleton  of  a  bird  is  remarkable 
for  the  rapidity  of  its  ossification.  It  is  worthy  of  note  that  other 
parts  of  the  bodies  of  adult  birds  also  become  ossified.  Among  such 
parts  are  the  tendons  of  the  muscles  of  the  legs,  of  the  feet,  and  of  the 

1  Greatful  acknowledgment  is  hereby  made  to  Dan  M.  McCarty,  Chemist, 
Animal  Industry  Division,  North  Carolina  Agricultural  Experiment  Station,  for 
this  analysis. 


22 


ANATOMY   OF   THE   DOMESTIC   FOWL 


neck;  the  plates  of  the  corneal  margin  of  the  sclerotic  tunic  of  the 
eye;  and  the  stapes  of  the  ear.  Ossification  in  birds  at  the  attach- 
ments of  the  semi-lunar  valves  of  the  aorta  and  of  the  pulmonary 
artery  has  been  reported  by  Owen. 

The  bony  structure  is  compact,  and  the  bones  contain  a  greater 
proportion  of  phosphate  of  lime  than  do  the  osseous  structures 
of  mammals.  Especially  is  this  the  case  in  those  parts  of  the 
skeleton  which  are  permeated  by  air. 

THE  DIVISIONS  OP  THE  SKELETON 

(Cranium 
Face 
The  Axial  skeleton     I  Cervical  region 

-n        i       -      !Ribs 
Dorsal  region  1  OA 

I  Sternum 
Lumbar  region 
Sacral  region 
Coccygeal  region 


The  Vertebral  column 


The  Appendicular  skeleton 


Shoulder  girdle 


Scapula 
Coracoid 


Fore  limb 


Pelvic  girdle 
(Hip  bone) 


Hind  limb 


Clavicle 
Arm  {Humerus 

Radius 
Forearm 

Ulna 
Carpus 
Hand     Metacarpus 

Phalanges 
Ilium 
Ischium 
Pubis 
Thigh  {Femur 

Tibia 
Leg 


Foot 


Fibula 
Metatarsus 

Phalanges 


The  bodies  of  birds  contain  many  air  reservoirs  to  make  them 
light  that  flying  may  be  more  easy.  Many  bones  have  their  weight 
in  proportion  to  size  and  strength  thus  greatly  reduced.  In  very 
young  birds  the  cavities  of  bones  contain,  instead  of  air  spaces, 
loosely  arranged  red  marrow,  which  is  in  most  bones  later  absorbed. 


OSTEOLOGY  23 

The  air  reservoirs  in  bones  are  most  capacious  in  the  best  flyers. 
In  the  non-flyers  more  of  the  bones  retain  their  red  marrow. 

The  bones  supplied  with  air  spaces  are  relatively  larger  than 
in  mammals,  and  are  provided  with  small  transverse  osseous  columns 
which  cross  in  different  directions  and  from  side  to  side.  These  cross 
beams  give  stability  to  the  thin  wall  of  the  bone.  The  membranes 
lining  these  cavities  are  very  vascular. 

THE  AXIAL  SKELETON 
THE  SKULL 

The  skull  is  divided  into  the  cranial  and  facial  portions.  In 
these  parts  we  find  present  31  bones:  one  occipital,  two  parietal,  two 
frontal,  one  ethmoid,  one  sphenoid,  and  two  temporal;  all  of  which 
constitute  the  cranial  group;  two  premaxillary,  two  maxillae,  two 
nasal,  two  lacrimal,  two  palatine,  two  pterygoid,  two  zygomatic, 
one  vomeral,  the  two  jugal,  and  two  quadrato-jugal,  which  constitute 
the  facial  group;  two  quadrati  and  one  inferior  maxillary,  which 
constitute  the  inferior  jaw  group. 

The  peculiarities  of  the  skull  are  the  long  os  incisivum  and  the 
single  condyle  located  on  the  occipital  bone  just  below  the  foramen 
magnum.  The  condyle  articulates  with  the  atlas. 

The  head  of  the  bird  is  small  in  proportion  to  the  size  of  the 
body,  and  in  front  it  is  conical  in  shape. 

THE  CRANIUM 

The  cranial  cavity,  or  cavum  cranii,  incloses  the  brain  with  its 
membranes  and  vessels. 

The  dorsal  wall,  or  roof,  is  formed  by  the  frontal  and  the  parietal 
bones.  In  the  median  line  of  the  cerebral  portion  is  the  internal 
parietal  crest.  The  roof  of  the  cerebellar  portion  is  marked  centrally 
by  a  groove. 

The  posterior  wall  of  the  cerebellum  is  formed  by  the  occipital 
bone. 

The  lateral  wall  is  formed  chiefly  by  the  temporal  bone.  It  is 
marked  by  a  ridge  which  divides  the  cavity  into  the  cerebral  and 
cerebellar  compartments.  The  cerebral  portion  is  marked  by  a 
depression  which  receives  the  optic  lobes.  A  crest  divides  this 
cavity  from  the  optic  portion.  The  walls  are  marked  by  digitations 
and  vascular  grooves. 


24  ANATOMY   OF   THE  DOMESTIC   FOWL 

j 


52. 


FIG.  4. — The  skeleton  of  the  domestic  fowl,  i,  Os  incisivum.  2,  External 
nasal  opening.  3,  Os  nasale.  4,  Os  lachrymale.  5,  Lamina  perpendicularis. 
6,  Os  dentale.  7,  Os  palatine.  8,  Os  quadrato-jugal.  9,  Os  pterygoideum.  10, 
Os  quadratum.  u,  Os  articulare.  12,  External  auditory  canal.  13,  Atlas. 
14,  Os  carpi  radiale.  15,  Radius.  16,  First  finger.  17,  Os  metacarpus.  18, 
Second  finger.  19,  Third  finger.  20,  Os  carpi  ulnare.  21,  Ulna.  22,  Humerus. 
23,  Thoracic  vertebras.  24,  Scapula.  25,  Os  ilium.  26,  Foramen  ischiadicunu 
27,  Caudal  vertebra?.  28,  Pygostyle.  29,  Foramen  obturatum.  30,  Osischium. 
31,  Processus  uncinatus.  32,  Vertebral  rib.  33,  Os  claviculum  or  furculum. 
34,  Os  coracoideum.  35,  Os  femoris.  36,  Os  pubis.  37,  Body  of  sternum.  38, 
Lateral  internal  process  of  sternum.  39,  Costal  process  of  sternum.  40,  Sternal 
crest,  cristi  sterni,  or  keel  of  breast-bone.  41,  Sternal  rib.  42,  Lateral  external 


OSTEOLOGY  25 

The  ventral  wall,  floor,  or  basis  cranii  interna,  may  be  regarded 
as  forming  five  fossae.  These  are:  one  anterior,  one  middle,  one 
posterior,  and  two  lateral.  The  anterior  fossa  supports  the  frontal 
and  olfactory  parts  of  the  cerebrum.  It  lies  at  a  higher  level  thai! 
the  middle  fossa.  The  middle  fossa,  or  fossa  cranii  media,  is  circular 
in  outline  and  extends  into  the  lateral  fossae  which  lodge  the  ol- 
factory lobes.  Just  back  of  the  middle  fossa  is  the  sulla  turcica, 
upon  which  rests  the  pituitary  body.  The  posterior  fossa,  or  fossa 
cranii  posterior,  lodges  the  medulla  oblongata. 

Bones  of  the  Cranium  (Figs.  4,  6,  7,  and  8). — The  bones  of  the 
cranium  fuse  early  in  the  chick's  life.  The  sutures  uniting  the 
bones  can  usually  be  seen  in  the  fetus  or  in  the  baby  chick  soon 
after  it  emerges  from  the  shell.  The  major  portion  of  the  cranial 
bones  become  entirely  fused.  Each  cranial  and  each  facial  bone 
ossifies  from  a  distinct  center  or  centers. 

The  cavity  for  the  cerebrum  is  much  larger  than  the  cavity 
for  the  cerebellum.  The  cranial  cavities  in  birds  are  relatively 
larger  than  in  mammals.  The  bones  are  designated  as  in  mammals. 
There  are  three  single  bones,  the  occipital,  the  ethmoid,  and  the 
sphenoid.  Those  in  pairs  are  the  frontal,  the  parietal,  and  the 
temporal. 

The  Occipital.  Location. — The  occipital  bone  or  os  occipitale, 
is  situated  at  the  posterior  part  of  the  cranium,  of  which  it  forms  the 
posterior  wall.  This  part  is  called  the  base  of  the  cranium.  The 
occipital  bone  articulates  with  or  touches  inferiorly,  the  sphenoid, 
laterally,  the  temporal,  and  superiorly,  the  parietal. 

Development. — The  occipital  bone  is  developed  from  four  centers 
of  ossification;  the  dorsal,  or  os  occipitale  superius,  two  lateral,  or 
ossa  occipitales  laterales,  and  the  ventral,  or  os  occipitale  inferius, 
all  of  which  may  be  seen  distinct  in  the  baby  chick  (Fig.  5,  Part  II, 
No.  i). 

Description. — In  the  center  of  the  occipital  bone  is  the  foramen 
magnum.  Through  this  foramen  the  spinal  cord  extends  into 
the  cranial  cavity  and  connects  with  the  medulla  oblongata.  The 
occipital  bone  has  a  single  condyle,  which  is  located  just  below  the 

process  of  sternum.  43,  Os  fibula.  44,  Zyphoid  process  of  sternum.  45,  In- 
ternal notch.  46,  Os  patella.  47,  Os  tibia.  48,  Os  metatarsus.  49,  Second 
toe.  50,  Fourth  toe.  51,  Os  metatarsale.  52,  First  toe.  53,  Second  toe.  54, 
Second  phalanx  of  second  finger.  55,  Os  meta  carpus.  56,  Air  opening  in 
humerus.  57,  Hypocledium.  58,  External  notch.  59,  Cervical  vertebrae.  60. 
Foramen  oblongum. 


26 


ANATOMY   OF   THE   DOMESTIC   FOWL 


' 


coo 


FIG.  5. — Bones  of  the  head  and  vertebra. 

Part  I. — i,  The  cranium.  2,  The  skull  cap.  3,  The  ethmoid  bone.  4,  The 
inferior  maxilla.  5,  The  palatine  bone.  6,  The  quadrato-jugal.  7,  The  jugal. 
8,  The  superior  maxilla.  9,  The  premaxilla.  10,  The  horny  covering  for  the 
premaxilla.  u,  The  horny  covering  for  the  os  dentale.  12,  The  os  quadratum. 
13,  The  nasal  bone.  14,  The  pterygoid. 

Part  II. — i,  The  os  occipitale  (i,  dorsal;  2,  two  lateral;  3,  ventral  portions 
and  4,  foramen  magnum) .  2,  The  fourteen  cervical  vertebrae,  (i,  atlas;  2,  axis) . 
3,  The  seven  dorsal  vertebrae.  4,  The  fourteen  lumbo-sacral  vertebrae.  5,  The 
seven  coccygeal  vertebrae.  6,  The  pelvis  (i,  ilium;  2,  ischium;  3,  pubis;  4,  cotyloid 
cavity  or  acetabulum).  7,  The  vertebral  column  complete  from  the  baby  chick. 
8,  The  parietal  bone.  9,  The  temporal  bone.  10,  The  frontal  bone. 


OSTEOLOGY  27 

foramen  magnum  and  articulates  with  the  atlas.  At  the  base  of 
the  condyle  a  small  subcondyloid  fossa  receives  the  body  of  the  atlas 
during  extreme  flexion  of  the  head.  In  the  center  of  the  lateral 
wing  of  the  occipital  bone  there  is  a  small  foramen  through  which_ 
passes  the  hypoglossal  nerve.  Somewhat  laterally  from  this  foramen 
there  is  an  opening  through  which  the  vagus,  or  pneumogastric 


PIG.  6. — View  of  the  frontal  region  of  the  skull  of  a  hen.     I,  Parietal.      2 
Frontal.     3,   Nasal.     4,  Premaxilla.     5,  Temporal.     6,  Inferior  jaw.     7,  Jugal 

bone. 


nerve  passes.  Laterally  from  these  is  the  canalis  caroticus  et  ju- 
gularis.  Between  the  os  occipitale  superius,  or  dorsal  portion, 
and  the  ossa  parietalia  is  a  space  to  which  ligaments  are  attached, 
called  the  fontanel. 

The  Ethmoid.  Location. — The  ethmoid,  or  os  ethmoidale, 
forms  the  anterior  wall  of  the  cranium,  and  the  orbital  septum. 
It  is  related  anteriorly  with  the  vomeral,  superiorly  with  the  nasal 


28  ANATOMY   OF   THE   DOMESTIC   FOWL 

and  frontal,  posteriorly  with  the  temporal,  and  inferiorly  with  the 
sphenoid,  and  palatine. 

Description. — The  ethmoid  consists  of  a  perpendicular  and  a 
horizontal  lamina.  The  perpendicular  lamina,  located  between 
the  orbital  cavities,  is  cajled  the  septum  inter orbitale.  On  each  side 
of  the  septum  interorbitale  and  near  the  superior  orbital  roof  are 
two  foramina  for  the  passage  of  the  olfactory  nerves.  In  the  hori- 
zontal plate,  which  forms  the  anterior  cranial  wall,  are  located  the 
optic  foramina  through  which  pass  the  optic  nerves. 


FIG.  7. — Side  view  of  the  skull  of  a  hen.  i,  Lamina  perpendicularis.  2, 
Foramen  for  the. passage  of  the  nerve  of  smell.  3,  Foramen  for  the  passage  of 
the  optic  nerve.  4,  Nasal  bone.  5,  External  nasal  opening.  6,  Premaxilla 
7,  Os  dentale.  8,  Superior  maxilla.  9,  Os  jugal.  10,  Os  quadrato-jugal.  n, 
Os  quadratus.  12,  Pterygoideus.  13,  Os  articulare.  14,  Inferior  maxilla.  15, 
Temporal.  16,  External  auditory  canal.  17,  Parietal.  18,  Frontal.  19,  Pala- 
tine. 20,  Orbital  process,  posterior  to  which  is  the  processus  zygomaticus. 

21,  Interorbital   foramen   and    optic    foramen'    for    passage    of    optic    nerve. 

22,  Attachment  for  inferior  oblique;  23,  for  superior  oblique;  24,  for  levator 
palpebrae  superioris;  25,  for  internal  rectus;  26,  for  superior  rectus;  27,  for  external 
rectus;  28,  for  inferior  rectus;  28,  for  inferior  rectus;  29,  for  depressor  palpebrae 
inferioris;  30,  for  orbicularjs  palpebrarum;  31,  for  tensor  tympani;  32,  for  circum- 
concha. 

The  Sphenoid.  Location. — The  sphenoid,  or  os  sphenoidale, 
forms  the  floor  of  the  cranial  cavity  and  articulates  with  or  touches 
posteriorly  the  occipital,  laterally  the  temporal,  and  anteriorly  the 
palatine,  and  ethmoid. 

Description. — The  sphenoid  bone,  the  largest  part  of  the  cranial 
floor,  is  formed  by  the  fusion  of  the  nasal  and  the  cranial  parts.  It  is 
a  three-cornered  bone  with  two,  thin,  broad  wings.  These  wings 
are  divided  into  two  portions,  orbital  wings,  or  alee  orbitales,  and 


OSTEOLOGY  29 

temporal  wings,  or  alee  temporales.  The  temporal  wing  forms  a 
cover  for  the  Eustachian  tube  trumpet,  and  for  the  canal  coming 
from  the  sella  turcica,  which  latter  gives  passage  to  the  intracranial 
carotid  artery.  The  orbital  wing  forms  the  lower  portion  of  trre 
posterior  wall  of  the  orbital  cavity,  and  lies  directly  before  the  os 
petrosum  or  temporal  bone  where  the  second  and  third  branches 
of  the  fifth  pair  of  cranial  nerves  emerge  from  the  cranial  cavity. 

Anteriorly  the  sphenoid  has  a  foramen  for  the  passage  of  the 
Eustachian  tube,  the  tuba  auditiva,  and  also  a  sharp-pointed  projec- 
tion, the  nasal  portion,  called  the  rostrum. 

The  Frontal.  Location. — The  frontal  bones,  or  ossa  frontales,  two 
in  number,  form  the  forehead,  a  portion  of  the  nose,  and  a  portion 
of  the  roof  of  the  orbital  cavities.  They  are  related  posteriorly  with 
the  parietal,  laterally  with  the  temporal  and  zygomatic,  and  ante- 
riorly with  the  nasal  and  premaxillary.  They  touch  inferiorly  the 
ethmoid. 

Description. — Each  of  these  bones  has  a  processus  orbitalis  which 
is  seen  at  the  outer  margin  of  the  posterior  and  upper  orbital  wall 
and  just  in  front  of  the  zygomatic  process  of  the  squamous 
portion  of  the  temporal.  The  frontal  bone  forms  the  anterior 
portion  of  the  superior  wall  of  the  cranial  cavity.  The  two  bones  are 
thin,  flat,  and  meet  at  the  median  line  of  the  forehead.  The  external 
surface  is  convex.  The  inner  surface  has  a  ridge  located  longitudi- 
nally and  in  the  center  the  bone  becomes  narrow  anteriorly. 

The  Parietal.  Location. — The  parietal  bones,  or  ossa  parietalia, 
two  in  number,  form  the  posterior  part  of  the  roof  of  the  cranial 
cavity.  They  meet  in  the  median  line  and  are  related  posteriorly 
with  the  occipital,  anteriorly  with  the  frontal,  and  laterally  with  the 
temporal  bones. 

Description. — The  parietal  bones  are  short  and  very  broad  (Fig. 
5,  Part  II,  No.  8).  Each  bone  is  quadrilateral  in  outline  and  has 
two  surfaces,  four  borders  and  four  angles.  The  external  parietal 
surface  is  convex  and  smooth  and  the  internal,  cerebral  surface  is 
concave. 

The  Temporal.  Location. — The  temporal  bones,  or  ossa  temporales, 
two  in  number,  are  located  at  the  lateral  portion  of  the  cranium,  and 
aid  in  the  formation  of  the  cranial  wall.  The  temporal  bone  is  related 
posteriorly  with  the  occipital,  superiorly  with  the  parietal  and  fron- 
tal, externally  with  the  quadratus,  anteriorly  with  the  ethmoid,  and 
inferiorly  with  the  sphenoid. 


30  ANATOMY   OF   THE   DOMESTIC   FOWL 

Description. — The  temporal  bones  consist  of  the  fused  squamous 
and  petrous  temporals;  they  contain  the  essential  organs  of  hearing. 

The  squamous  portion  of  the  temporal  bone  possesses  the  long 
thin  zygoma  tic  process  sometimes  called  the  posterior  orbitalis. 
It  forms  a  small  flattened  tongue,  directed  forward,  sometimes 
free,  and  at  other  times  united  by  its  superior  border  to"  the 


FIG.  8. — Inferior  view  of  the  skull  of  a  hen.  i,  Occipital.  2,  Foramen  mag- 
num. 3,  Occipital  condyle  and  just  below  the  basi-occipital.  4,  Foramen  for 
the  passage  of  the  hypoglossal  nerve.  5,  Foramen  for  the  passage  of  the  vagus. 
6,  Canalis  caroticus  and  jugulare.  7,  Sphenoid.  8,  Temporal  wings  of  the 
sphenoid.  9,  Foramen  auditiva.  10,  Os  articulare.  n,  Os  angulare.  12, 
Vomer.  13,  Os  dentale.  14,  Pterygoid. 

summit  of  the  orbital  process.  This  is  especially  true  in  the  turkey. 
This  process  is  seen  near  the  lower  outer  portion  of  the  posterior 
orbital  wall.  The  squamous  portion  is  also  provided  antero- 
laterally  with  an  articular  facet  which  articulates  with  the  quadrate 
bone.  The  large  portion  of  the  temporal  bone  lies  on  the  side  of 


OSTEOLOGY  31 

the  cranium  superior  to  the  ala  sphenoida  temporale.  It  extends 
outward  and  anteriorly  over  the  rims  of  the  petrosum  and  'ala 
sphenoida  orbitale.  The  squamous  part  forms  the  upper  three- 
fourths  of  the  cochlea,  the  inner  auditory  canal,  the  upper  partTrf 
the  fenestra  ovalis,  the  anterior  vertical  and  the  outer  semicircular 
canal,  and  the  lower  part  of  the  posterior  vertical  semicircular  canal. 

The  petrous  portion  forms  the  posterior  wall  of  the  foramen 
ovale  and  the  fenestra  ovalis  in  which  lies  the  columella.  The 
fenestra  ovalis  and  the  fenestra  rotunda  are  the  only  two  entrances 
into  the  labyrinth.  In  this  region  may  be  seen  the  fusion  line 
between  the  os  petrosum  and  the  os  occipitale.  Superiorly  and 
posteriorly  the  petrous  portion  touches  the  external  parietalia 
and  occipitalis;  infero-laterally  it  unites  with  the  basi-sphenoid. 
The  outer  rim  of  the  foramen  ovale  is  broadened  by  the  ala  sphen- 
oida and  mesially  by  the  basi-sphenoid.  This  foramen  gives  exit 
to  the  second  and  third  divisions  of  the  fifth  pair  of  cranial  nerves. 

The  lateral  surface  of  the  temporal  bone  presents  a  short  tube, 
the  external  acoustic  process,  or  processus  acusticus  externus,  to 
which  is  attached  the  concha  of  the  ea.r.  The  process  is  directed 
outward.  Its  lumen,  the  external  acoustic  meatus,  or  meatus  acus- 
ticus  externus,  conducts  to  the  cavity  of  the  middle  ear  in  the  bare 
skull,  but  is  separated  from  it  by  the  tympanic  membrane  in  the 
natural  state. 

BONES  OF  THE  FACE 

The  bones  of  the  face,  or  ossa  faciei,  are  the  premaxillary,  or 
upper  mandible,  the  maxillae,  the  nasal,  the  lacrimal,  the  palatine, 
the  pterygoid,  the  zygomatic,  the  vomeral,  the  jugal  and  the 
quadrato-jugal.  The  vomer  is  single,  the  others  are  paired.  In  the 
inferior  maxillary  group  there  are  the  quadrati,  and  the  inferior 
maxillary,  or  lower  mandible.  The  turbinated  and  hyoid  bones 
are  also  discussed  with  the  bones  of  the  face. 

The  beak  consists  of  the  anterior  portion  of  the  upper  and  lower 
mandibles  which  are  covered  with  a  horny  structure. 

The  Premaxilla.  Location. — The  premaxillse,  or  ossa  incisiva, 
or  mandibular  structures,  are  located  in  the  extreme  anterior 
facial  region. 

Description. — The  premaxillae  are  long  and  the  anterior  end 
is  pointed.  Each  consist  of  two  lateral  halves  which  become  fused 
before  the  chick  is  hatched.  They  partly  circumscribe  the  openings 


32  ANATOMY   OF   THE   DOMESTIC   FOWL 

into  the  nose.  This  bone  is  the  base  of  the  upper  portion  of  the 
beak  and  determines  its  form.  It  forms  the  anterior  walls  of 
the  nasal  cavity.  It  has  between  the  nasal  bones,  two  processes 
which  extend  back  to  the  anterior  point  of  the  cerebral  cavity. 
The  posterior  part  of  the  incisivum  and  nasale  are  flat,  thin,  and 
elastic.  The  extensions  then  are  the  processus  maxillaris,  the 
processus  palatinus,  and  the  processus  frontalis,  the  first  of  which 
forms  part  of  the  jaw  rim,  the  second,  which  aids  in  forming  the 
gum  plate,  and  the  last  which  reaches  to  the  anterior  portion  of  the 
cranial  wall. 

The  Maxilla.  Location. — The  superior  maxillaries,  or  ossa  maxil- 
lares,  two  in  number,  form  the  floor  of  the  upper  beak,  a  part  of 
the  palatine  roof  and  nasal  walls. 

Each  maxilla  borders  laterally  the  premaxilla  and  the  nasal; 
inferiofly,  the  anterior  point  of  the  palatine;  and  posteriorly,  the 
jugale. 

Description. — The  maxillae  are  thin,  flat,  bones.  They  have 
three  borders  and  three  angles.  The  palatine  processes  of  the  two 
bones  do  not  meet  in  the  median  line,  which  results  in  a  cleft  in 
the  median  palatine  region.  The  bone-like  gums  are  formed  partly 
by  the  palatine  processes  but  more  largely  by  lateral  wings  of  the 
os  incisivum.  Each  maxilla  has  posteriorly  a  yoke-like  extension, 
superiorly  a  small  extension,  and  also  a  palatine  process.  The 
latter  articulates  by  a  facet  with  the  vomer 

The  Nasal.  Location. — The  nasal  bones,  or  ossa  nasalia,  two 
in  number,  are  located  in  the  lateral  facial  region.  The  nasal  bone 
articulates  posteriorly  with  the  frontal;  laterally,  on  the  inner 
border,  with  the  processus  frontalis  of  the  premaxilla,  and  on  the 
outer  border  with  the  lacrimal;  and  inferiorly  with  the  premaxilla, 
maxilla,  jugale,  and  vomer. 

Description. — The  nasal  bone,  or  os  nasale,  is  broad,  flat,  and 
elastic  and  forms  the  posterior  wall  of  the  nasal  opening.  Under 
this  bone  is  located  the  infraorbital  sinus. 

There  are  three  extensions:  first,  the  processus  intermaxillaris, 
which  forms  the  upper  wall  of  the  nasal  cavity;  second,  the  processus 
maxillaris  anterior,  directed  downward  and  forward,  which  fuses 
with  the  maxillary  bone  and  forms  the  posterior  rim  of  the  nasal 
cavity;  and  third,  a  posterior  processus  frontalis,  which  lies  parallel 
with  the  ethmoid. 

The  Lacrimal.    Location. — The  lacrimal  bones,  or  ossa  lacrimalia, 


OSTEOLOGY  33 

two  in  number,  are  located  at  the  outer  border  and  at  the  junction 
of  the  processus  frontalis  of  the  nasal,  with  the  frontal  bone. 

Description. — The  lacrimal  bone  is  small,  and  rather  filiform. 
They  become  fused  with  the  nasal  and  the  frontal  bones,  forming 
part  of  the  margin  of  each. 

The  Palatine. — Location.  The  palatine  bones,  or  ossa  palatina, 
two  in  number,  enter  into  the  formation  of  the  inner  part  of  the  bony 
gum  and  hard  palate,  or  roof  of  the  mouth.  They  form  the  support 
for  the  hard  palate.  Each  palatine  articulates  posteriorly  with 
the  rostrum,  or  nasal  portion  of  the  sphenoid,  and  with  the  pterygoid; 
and  anteriorly  with  the  maxilla. 

Description. — The  palatine  bone  is  curled  posteriorly  and  is  thin 
at  the  upper  portion  and  thick  at  the  lower  border.  Anteriorly 
it  has  a  long  rather  filiform  projection. 

The  Pterygoid.  Location. — The  pterygoid  bones,  or  ossa  ptery- 
goidea,  two  in  number,  are  located  back  of  the  region  of  the 
posterior  nares.  They  extend  diagonally  outward  and  backward 
from  the  median  region  of  the  sphenoid  rostrum  to  the  quadrate 
bone.  They  articulate  anteriorly  with  the  sphenoid  rostrum  and 
the  palatine,  and  posteriorly  with  the  quadrate. 

Description. — The  pterygoid  bones  are  slender  and  cylindrical, 
.and  are  expanded  at  the  ends  into  an  articular  facet. 

The  Zygomatic.  Location. — The  zygomatic,  or  ossa  zygomatica, 
two  in  number  are  situated  below  the  orbital  cavity  and  extend 
from  the  maxilla  to  the  quadrate  bone. 

Description. — The  zygomatic  is  small,  slender,  rod-shaped,  and 
forms  the  lateral  portion  of  the  upper  jaw.  The  anterior  portion 
of  the  zygomatic  represents  the  jugal  and  is  fused  with  the  max- 
illa and  with  the  anterior  processus  maxillaris  of  the  nasal  bone, 
the  maxilla,  and  the  posterior  portion,  the  quadrato-jugal,  which 
articulates  with  the  quadrate  bone. 

The  Voiner.  Location. — The  vomer  is  located  in  the  median 
nasal  septum.  It  articulates  with  the  rostrum  of  the  sphenoid, 
l>eing  connected  to  it  by  a  mass  of  ligaments.  It  touches  ante- 
riorly the  posterior  portion  of  the  maxilla. 

Description. — The  vomer  is  a  median  bone  and  aids  in  the  forma- 
tion of  the  septum  nasi.  It  consists  of  a  thin  plate,  thickest  pos- 
teriorly and  diminishing  toward  the  anterior  edge. 

The  Jugal  and  Quadrato-jugal. — The  jugal  and  quadrato-jugal 
are  united  forming  a  long  slender  cylindrical  bone  called  the  zygo- 


34  ANATOMY   OF   THE   DOMESTIC   FOWL 

ma  tic,  lying  at  the  outer  side  of  the  upper  jaw.  They  have  been 
described  under  zygomatic,  which  see. 

The  Quadrate.  Location. — The  quadrate  bones,  or  ossa  quadra ta, 
two  in  number,  are  located  antero-laterally  to  the  temporal  bones. 
Each  articulates  inferiorly  with  the  posterior  articular  portion,  or 
pars  articulare,  of  the  inferior  maxilla  and  infero-laterally  with 
the  quadrato-jugalare  portion  of  the  zygomatic.  It  articulates 
antero-internally  with  the  pterygoid  and  supero-posteriorly  with 
the  temporal. 

Description. — The  quadrate  bone  is  anvil-like  in  shape.  It 
has  an  anterior  process,  the  orbital  process,  for  muscular  attach- 
ments, and  posteriorly  it  affords  attachment  to  the  ear  drum. 

The  Inferior  Maxilla.  Location. — The  inferior  maxilla,  lower  jaw, 
or  os  maxillare  inferius,  also  called  the  mandibular  bone,  or  pars 
dentis,  is  analogous  to  the  lower  jaw  of  mammals.  It  articulates 
posteriorly  with  the  quadrate  bone. 

Description. — The  inferior  maxilla  is  the  largest  bone  of  the  face. 
It  is  made  up  of  a  right  and  a  left  limb  which  are  separate  in  the  fetus 
and  which  unite  subsequently  anteriorly,  forming  the  inferior  por- 
tion of  the  beak.  Each  limb  of  the  jaw  is  developed  from  five  ele- 
ments: the  pars  articularis,  which  forms  the  jaw-joint  and,  expanded, 
articulates  with  the  quadrate  bone;  the  pars  angularis,  lying  just  in 
front  of  the  pars  articularis ;  the  pars  supra-angularis,  a  slender  bone 
lying  just  above  the  angularis;  the  splenial,  a  thin  plate  of  bone, 
lying  along  the  inner  surface  of  the  mandible;  and  the  pars  dentalis, 
which  forms  the  anterior  portion  of  the  jaw. 

The  Turbinate  Bones.  Location.— The  turbinate  bones,  or  ossa 
turbinata,  six  in  number,  are  attached  to  the  lateral  walls  of  the 
nasal  cavity  (Fig.  26,  No.  A,  i  and  2).  In  each  nasal  cavity  there  are 
three  turbinate  bones,  one  anterior  and  two  posterior.  Of  the  two 
posterior  the  upper  one  lies  supero-posterior  to  the  inferior  one. 
The  turbinate  bones  are  attached  to  the  lateral  nasal  walls,  project 
into  the  cavity  and  thus  greatly  diminishing  its  extent. 

Description. — Each  turbinate  bone  is  composed  of  a  very  thin 
lamina,  finely  cribriform  in  many  places,  and  in  the  fresh  state, 
covered  on  both  sides  with  mucous  membrane.  These  bones  are 
curled  and  partly  membrano-cartilaginous  structures  which  give 
greater  surface  in  the  nasal  passage  for  mucous  membrane  in  which 
the  olfactory  nerve  terminal  filaments  are  distributed. 


OSTEOLOGY  35 

The  Nasal  Cavity. — The  nasal  cavity,  or  cavum  nasi,  is  a  lon- 
gitudinal passage  which  extends  through  the  upper  part  of  the. face. 
It  is  divided  into  right  and  left  halves  by  a  median  septum  nasi. 
Its  walls  are  made  up  of  the  premaxilla,  maxilla,  nasal,  vomer,arnd 
palatine  bones. 

The  Hyoid  Bone.  Location. — The  hyoid  bone,  or  os  hyoideum, 
is  situated  chiefly  between  the  rami  of  the  mandible,  but  its  upper 
part  extends  around  the  outer  margin  of  the  base  of  the  skull.  The 
hyoid  bone  does  not  articulate  with  any  bones  of  the  skull,  but  is 
firmly  attached  by  strong  fibrous  structure. 

Description. — The  hyoid  bone  consists  of  the  following  parts: 
the  body,  or  basi-hyal,  which  is  subcylindrical  and  presents  in  front 
a  trochlear  articular  surface,  convex  transversely,  and  concave 
vertically  for  articulation  with  the  ewer-shaped  portion  of  the  glosso- 
hyal.  The  anterior  free  portion,  or  lingual  process,  is  called  the 
glosso-hyal,  or  entoglossal  bone.  The  lingual  process  gives  support 
to  the  muscular  and  fibrous  structures  of  the  tongue.  On  either 
side  of  the  basi-hyal  there  is  a  limb  passing  posteriorly  along  the 
side  of  the  superior  larynx,  extending  upward  along  the  outer  border 
of  the  occipital  bone.  This  is  the  cornu  of  the  os  hyoideum  and  is 
divided  into  two  elements,  first,  the  basi-branchial  which  is  bone  and! 
articulates  with  the  basi-hyal,  and  the  second,  the  cerato-branchial, 
cartilaginous  in  structure.  In  the  center  and  projecting  backward 
from  the  body  of  the  os  hyoideum  is  a  spur  process  called  the  uro- 
hyal,  partly  bony  and  partly  cartilaginous,  and  which  rests  upon 
the  superior  larynx. 

THE  VERTEBRAL  COLUMN 

The  vertebral,  or  spinal  column  consists  of  42  bones,  as  shown  in 
the  following  table: 

Cervical  region 14 

Dorsal  region 7 

Lumbo-sacral  region 14 

Coccygeal  region 7 

Total 42 

Many  of  the  bones  of  the  dorsal  and  lumbo-sacral  regions  do  not 
have  free  articulations.  The  cervical  and  coccygeal  alone  have  free 
movements. 

The  Cervical  Vertebrae  (Fig.  4,  No.  59;  Fig.  5,  Part  II,  No.  2). 
Location. — The  cervical  vertebrae  form  the  neck  of  the  fowl. 


ANATOMY   OF   THE   DOMESTIC   FOWL 


FIG.  9. — Os  hyoidum  and  tongue  muscles.  I,  Glosso-hyal.  3,  Basi-hyal.  4, 
Basi-branchial  element  of  the  cornua.  5,  Cerato-branchial  element  of  the 
cornua.  6,  Uro-hyal  or  spur  process.  7,  Genio-hyoideus.  8,  Cerato-hyoideus 
showing  the  slender  tendon.  9,  Hyoideus  transversus.  10,  Hyoideus^trans- 
versus. 


OSTEOLOGY  37 

Description. — The  long  cervical  section  of  the  spinal  column  is 
S-shaped  and  is  made  up  of  fourteen  vertebrae.  The  anterior  seg- 
ments move  freely  forward,  the  middle  ones  backward  and  the  pos- 
terior ones  forward,  allowing  the  S-shaped  curve  of  the  neck.  The 
neck  is  flexible  so  that  it  is  possible  for  the  beak  to  reach  the  coccy 
geal  oil  gland.  The  bird  is  enabled  to  reach  the  feathers  on  all  parts 
of  the  body  to  cleanse  and  oil  them. 

The  Atlas.  Location. — The  first  cervical  vertebra  is  called  the 
atlas.  Anteriorly  it  articulates  with  the  single  condyle  of  the  oc- 
cipital bone.  Posteriorly  it  articulates  with  the  axis,  or  second 
cervical  vertebra. 

Description.— The  atlas  is  the  smallest  of  the  cervical  vertebras 
and  is  ring-shaped.  The  anterior  articular  surface,  half-moon 
in  shape,  forms  a  deep  articular  cavity.  The  joint,  called  a  ball- 
and-socket  joint,  makes  possible  movements  in  all  directions.  The 
condyle  of  the  occiput  also  touches  an  articular  end  of  the  odontoid 
process  of  the  axis,  or  second  cervical  vertebra.  Posteriorly  there 
projects  from  the  atlas  two  small  lateral  wings  possessing  articular 
facets  which  articulate  with  similar  facets  on  the  lateral  wings  of 
the  axis.  Posteriorly  the  body  of  the  atlas  is  also  provided  with  an 
articular  surface  which  articulates  with  a  similar  surface  on  the 
anterior  portion  of  the  body  of  the  axis. 

The  Axis.  Location. — The  axis  is  the  second  cervical  vertebra. 
It  articulates  anteriorly  with  the  atlas,  and  by  a  facet  on  the  extreme 
anterior  end  of  the  odontoid  process,  with  the  condyle  of  the  oc- 
cipital bone.  Posteriorly  it  articulates  with  the  third  cervical 
vertebra. 

Description. — The  body  of  the  axis  is  short.  The  upper  anterior 
portion  of  the  body  of  the  axis  is  provided  with  a  tooth-like  process 
called  the  odontoid  process.  There  are  two  anterior  lateral  wings 
provided  with  small  articular  facets  which  articulate  with  similar 
facets  of  the  atlas.  The  anterior  surface  of  the  body  of  the  axis 
forms  a  true  articulation  with  the  body  of  the  atlas. 

The  axis  is  provided  with  a  superior  and  an  inferior  spine.  There 
are  two  posterior  articular  processes  which  articulate  with  the 
prezygapophyses,  or  anterior  articular  processes,  of  the  third  cervical 
vertebra.  The  posterior  part  of  the  body  of  the  axis  forms  a  true 
articulation  with  the  body  of  the  third  cervical  vertebra. 

Other  Cervical  Vertebrae. — Beginning  with  the  axis,  the  body 
of  which  is  relatively  short,  the  body  of  each  succeeding  vertebra 


38  ANATOMY  OF   THE  DOMESTIC  FOWL 

is  longer  than  that  of  the  preceding.  The  articulations  of  each 
vertebra  with  adjoining  vertebrae  are  effected  by  means  of  di- 
arthrodial  facets,  convex  in  one  direction  and  concave  in  the  other. 
Between  the  bodies  of  the  vertebrae  are  pads  of  fibrous  cartilage. 
Above  these  bodies  and  inferior  to  the  neural  spines  extends  through- 


FIG.  10. — A.  Diagram  of  three  first  dorsal  vertebrae  and  scapular  arch-side  view. 

B.  Diagram  of  section  through  the  hemal  arch. 

'  A.  i.  First  dorsal  segment.  2,  Second.  3,  Third.  4  and  5,  Hemal  arches. 
6,  The  pleurapophyses  or  floating  ribs.  7,  The  third  pleurapophyses  or  dorsal 
vertebral  rib  articulating  with  the  hemapophysis  or  sternal  rib,  8,  and  this  in 
turn  with  the  wing  of  the  sternum  form  a  hemal  arch.  9,  The  sternum.  10, 
Intervertebral  foramen  through  which  the  nerves  pass,  n,  Articulation  with 
the  body  of 'vertebra  parapophyses.  12,  Articulation  with  transverse  process 
or  diapophyses.  13,  Oblique  process  or  zygapophysis.  14,  The  epipleural 
appendage. 

B.  i,  Hemal  or  inferior  spine  (hypapophysis).  2,  The  neural  arch.  3,  The 
pleurapophyses  or  rib.  4,  The  superior  or  neural  spine  or  neurapophysis  which 
aids  in  the  formation  of  the  anapophyseal  ridge.  5,  Parapophyseal  surface  for 
head  of  rib.  6,  Tubercle  of  rib  articulating  with  the  diapophysis.  7,  Lamina 
of  neurapophysis.  8,  Centrum.  9,  Hemal  arch. 

out  the  spinal  column  the  large  neural  canal  which  is  occupied  by 
the  spinal  cord.  Between  the  vertebral  segments  the  neural  canal 
is  exposed  superiorly,  since  here  the  neural  arches  do  not  completely 
bridge  the  canal.  These  spaces  are  protected  by  intervertebral 
ligaments. 

In  addition  to  the  superior  neural  spines  and  the  inferior  spines, 


OSTEOLOGY  39 

from  the  body  of  the  vertebra  project  lateral  processes,  and  anterior 
and  posterior  oblique  processes. 

All  cervical  vertebrae  except  the  atlas  and  the  axis  are  made  up  of 
the  following  parts:  a  body,  or  centrum,  a  neural  canal,  a  neural- 
arch,  a  superior  dorsal,  or  neural  spine,  or  neurapophysis,  which 
in  most  cervical  vertebras  is  only  slightly  developed,  two  oblique 
processes,  or  zygapophyses,  two  transverse  processes,  or  diapophyses 
(Fig.  10,  No.  12)  and  in  some  vertebrae  two  tubercles,  or  anapophyses 
above  the  posterior  zygapophyses.  The  prezygapophyses  are 
directed  upward  and  inward;  the  postzygapophyses  are  directed 
downward  and  outward.  The  inferior  spines  are  only  well  developed 
in  the  last  two  or  three  cervical  vertebrae. 

Between  vertebral  segments,  except  the  central  sacral  portion,  on 
each  side,  there  is  an  intervertebral  foramen  (Fig.  n,  No.  -4,4), 
through  which  pass  the  spinal  nerves.  In  the  central  portion  of  the 
sacrum  where  the  vertebrae  have  fused,  there  are  two  foramina  on 
each  side  for  each  original  vertebra,  one  located  above  the  other, 
the  upper  giving  passage  to  the  sensory  branch,  the  lower  to  the 
motor  branch  of  the  nerve. 

The  Dorsal  Vertebrae  (Fig.  4,  No.  23;  Fig.  n,  -4).  Location. — 
The  dorsal,  or  thoracic  vertebrae,  or  vertebrae  thoracicales,  aid  in 
forming  the  roof  of  the  chest  cavity. 

Description. — The  dorsal  vertebral  section  is  made  up  of  seven 
vertebrae,  with  strong  short  bodies.  The  first  and  sixth  dorsal 
segments  articulate  as  do  the  cervical,  by  the  bodies  and  oblique 
processes.  (Fig.  n,  No.  A,  3,  illustrates  the  oblique  processes.) 
The  seventh  dorsal  is  fused  with  the  first  lumbo-sacral  vertebra. 
The  second  to  the  fifth  inclusive  of  the  vertebrae  are  fused  together, 
and  the  superior  and  inferior  spinous  processes  are  fused  into  a 
prominent  plate-like  ridge. 

The  transverse  processes  of  the  dorsal  vertebrae,  from  the  second  to 
the  sixth,  are  well  developed  and  are  bridged  over  with  a  thin  layer  of 
bone.  The  ventral  spines  are  partly  fused  and  form  a  very  promi- 
nent and  continuous  ridge.  (Fig.  n,  No.  A,  i,  shows  the  fused 
superior  spines;  No.  2,  the  fused  inferior  spines;  and  No.  4,  the  inter- 
vertebral  foramina.) 

The  Lumbo-sacral  Vertebrae  (Fig.  5,  Part  II,  No.  4).  Loca- 
tion.— The  fused  lumbo-sacral  section  of  the  spinal  column  forms 
the  roof  of  the  pelvic  cavity. 

Description. — The  lumbo-sacral  region  consists  of  fourteen  verte- 


ANATOMY   OF   THE  DOMESTIC   FOWL 


FIG.   ii. — Bones  from  the  scapular  arch. 

A.  Dorsal  vertebra,     i.  Superior  spinous  ridge.     2,  Inferior  spinous  ridge.     3, 
Oblique  processes.     4,  Intervertebral  foramina.     5,  Articular  facette  for    head 
of  the  rib.     6,  Articular  facette  for  tubercle  of  the  rib.     7,  Articular  portion  of 
the  body. 

B.  Outer  surface  of  scapula. 

C.  Inner  surface  of    scapula,     i,    Thin  caudal  end.     2,    Articular  head.     4, 
Processus  furcularis.     5,  Processus  humeralis.     6,  Processus  coracoideus. 

£>.  Outer  surface  of  coracoid. 

E.  Inner  surface  of  coracoid.    "i,  The  furcular  tuberosity.     2,  Articular  facette 
for  articulation  with  the  sternum.     3,  Articular  surface  for  humerus  and  scapula. 

F.  Outer  surface  of  humerus  and  G  the  inner  surface  of  the  same.     I,  Trochan- 
teric  fossa.     2,  Oval  articular  head  at  proximal  end.     3,  Shaft.     4,  Distal  end 
showing  articular  condyles.     5,  Trochanter.     6,  Trochlea  for  ulna.     7,  Trochlea 
for  radius.     8,  Depression  or  fossa. 

H.  Section  through  the  median  plane  of  the  humerus  showing  the  delicate 
cross  partitions  illustrating  provisions  made  for  bones  provided  with  air-sac 
extensions. 


OSTEOLOGY  41 

brae  which  are  distinct  in  the  body  of  the  newly  hatched  chick,  but 
which  become  fused  soon  after  hatching.  With  these  vertebral 
segments  there  are  fused  the  last  dorsal  and  first  coccygeal  vertebral 
segments.  This  fusion  is  so  complete  that  the  segments  are  in- 
dicated only  by  the  intervertebral  foramina  on  the  sides  through 
which  the  spinal  nerves  pass,  and  by  transverse  markings  on  the 
inferior  surface  of  the  bodies. 

The  lumbo-sacral  vertebrae,  called  the  sacrum,  and  the  ilia  are 
fused.  The  dorsal  spines  of  the  vertebral  segments  are  indicated 
only  in  the  anterior  portion  where  they  are  fused,  forming  a  plate. 
There  are  no  prominent  ventral  spines. 

The  Coccygeal  Vertebrae  (Fig.  4,  No.  27).  Location. — The 
coccygeal  or  caudal  vertebrae,  or  vertebrae  coccygeae,  constitute  the 
bones  of  the  tail. 

Description. — There  are  seven  coccygeal  vertebrae.  The  last 
segment,  shaped  like  a  plough  share  and  therefore  called  thepygo- 
style,  is  the  largest  and  is  supposed  to  have  been  formed  by  the 
fusion  of  several  original  distinct  segments.  It  supports  the  coc- 
cygeal oil  gland  and  the  row  of  rudder  feathers,  or  rectrices,  which 
are  arranged  fan-wise. 

All  of  the  coccygeal  vertebrae  except  the  first  are  freely  movable, 
thus  allowing  the  tail  to  be  used  as  a  rudder  during  flight.  The 
lateral  spines  are  long  and  well  developed,  and  the  superior 
spines  are  bifurcated,  thus  giving  increased  surface  for  muscular 
attachment.  The  first  coccygeal  segment  is  fused  with  the  last 
lumbo-sacral  vertebra. 

THE  THORAX 

The  dorsal  vertebrae  superiorly,  the  ribs  laterally,  and  the  sternum, 
or  breast-bone  inferiorly,  form  the  skeleton  of  a  large  cavity  called 
the  thorax.  The  dorsal  vertebrae  have  been  described. 

The  Ribs  (Fig.  4,  No.  32;  Fig.  10,  A  and  B).  Location. — The 
ribs  form  the  lateral  bony  wall  of  the  thorax,  articulating  superiorly 
with  the  dorsal  vertebrae. 

Description. — The  ribs  are  arranged  in  order  of  length,  the  ultimate 
rib  being  the  longest.  From  anterior  to  posterior,  they  approach 
more  nearly  a  horizontal  position.  The  ribs  are  divided  into  the 
true  and  the  false.  The  true  ribs  articulate  with  the  sternum.  The 
false  ribs  do  not  touch  the  sternum;  they  are  floating.  The  true 
ribs  are  composed  of  two  parts,  a  vertebral,  or  dorsal,  and  a  sternal, 


42  ANATOMY    OF   THE   DOMESTIC   FOWL 

or  ventral.  The  vertebral  part,  or  extremitas  vertebrates,  is  provided 
with  an  articular  head,  or  caput  costa;  a  neck,  or  collum  costce; 
and  an  articular  tubercle,  or  tuber culum  cost®.  The  head  and 
tubercle  articulate  with  the  dorsal  vertebra.  Below  the  head  of 
each  rib  is  a  pneumatic  foramen. 

The  distal  extremity  of  the  dorsal  section  of  the  rib  articulates 
with  the  proximal  end  of  the  sternal  section  by  a  diarthrodial 
articulation. 

The  articulations  of  the  true  ribs  with  the  sternum  is  diarthrodial 
and  each  articulate  by  two  small  ridges  with  a  double  sternal  facet. 
The  first,  the  second,  and  the  seventh  ribs  are  floating,  or  false 
ribs.  The  first  rib .  articulates  with  the  quadrate  part  of  the  last 
cervical  vertebra  and  also  with  the  first  dorsal  vertebra.  The 
seventh,  the  last  rib,  articulates  with  the  under  side  of  the  anterior 
alar  part  of  the  ilium.  This  rib  is  situated  similarly  to  the  true  ribs ; 
but,  instead  of  articulating  directly  with  the  sternum,  the  lower  end 
lies  against  the  sternal  segment  of  the  rib  just  anterior  to  it. 

From  the  posterior  edge  of  the  second,  the  third,  the  fourth,  and 
the  fifth  ribs,  and  near  the  middle  of  the  dorsal  segment,  are  flat, 
uncinate,  bony  processes  which  project  upward  and  backward,  over- 
lying in  each  case,  the  succeeding  rib  and  giving  greater  surface  for 
muscular  attachments  and  greater  stability  to  the  thorax. 

The  Sternum  (Fig.  4,  No.  40;  Fig.  10,  No.  A,  9).  Location. — The 
sternum,  or  breast-bone  forms  the  inferior  portion,  or  floor  of  the 
thoracic  cavity. 

Description. — The  sternum  is  a  quadrilateral,  curved  plate  with 
processes  projecting  from  each  angle  and  from  the  middle  of  the 
anterior  and  posterior  borders.  The  posterior  medial  projection, 
or  metasternum,  is  the  longest,  and  has  a  tall,  plate-like  ridge — 
the  sternal  crest,  crista  sterni — running  along  its  ventral  surface. 
The  crest  serves  the  important  function  of  increasing  the  bony  area 
for  the  attachment  of  the  powerful  muscles  which  move  the  wings. 
The  anterior  medial  projection,  or  rostrum,  is  short,  and  pierced 
at  its  root  by  an  opening  from  which  extend  two  elongated,  saddle- 
shaped  depressions  into  which  the  end  of  the  coracoid  bones  are 
received. 

The  plate-like  process  of  bone,  the  posterior  lateral  process,  which 
projects  from  the  caudal  angles  of  the  sternum  soon  divides  into  two 
parts.  The  shorter  of  these,  the  oblique  process,  broadens  toward  its 
free  end  and  covers  the  sternal  segments  of  the  last  two  ribs.  The 


OSTEOLOGY  43 

sides  of  the  sternum  are  thus  provided  with  an  external  and  an  in- 
ternal process  forming  an  external  and  an  internal  notch.  These 
notches  are  bridged  over  by  a  broad  ligament,  to  which  the  muscles 
are  attached.  In  poor  flyers,  as  the  domestic  fowl,  these  notches 
are  large.  The  posterior  end  of  the  sternum  is  called  the  xiphoid 
process  or  processus  xiphoideus.  Anteriorly  the  sternum  is  provided 
with  lateral  external  processes,  the  cotsal  processes.  The  lateral 
borders  of  the  sternum  are  pitted  by  four  depressions  into  which 
the  sternal  segments  of  the  ribs  are  received.  The  dorsal,  or  inner 
surface  of  the  bone  is  pierced  by  openings  by  which  the  air-sacs 
communicate  with  the  interior. 

THE  APPENDICULAR  SKELETON 

The  appendicular  skeleton  consists  of  the  shoulder  girdle,  the  fore 
limb,  the  pelvic  girdle,  or  hip  bone,  and  the  hind  limb.  The  shoulder 
girdle  consists  of  the  scapula,  the  coracoid,  and  the  clavicle.  The  fore 
limb  consists  of  the  arm,  forearm,  and  the  hand.  The  arm  consists 
of  the  humerus,  the  forearm  of  the  radius  and  the  ulna;  and  the  hand 
consists  of  the  carpus,  the  metacarpus,  and  the  phalanges.  The 
pelvic  girdle  consists  of  the  ilium,  the  ischium,  and  the  pubis.  The 
hind  limb  consists  of  the  thigh,  the  leg,  and  the  foot.  The  thigh 
consists  of  the  femur,  and  the  leg  consists  of  the  tibia  and  the  fibula. 
The  foot  consists  of  the  metatarsus  and  the  phalanges. 

THE  SHOULDER  GIRDLE 

The  shoulder  girdle  consists  of  the  scapula,  the  clavicle  and  the 
coracoid. 

The  Scapula.  Location.— The  scapula  (Fig.  n,  A,  B)  lies  on  the 
outer  and  superior  rib  surface,  extending  parallel  with  the  dorsal 
vertebrae. 

Description. — The  scapula  is  a  thin,  sword-like  bone,  becoming 
thicker  as  it  approaches  the  shoulder-joint.  The  scapula  expands 
and  becomes  thin  near  the  free  end,  which  reaches  nearly  to  the 
antero-lateral  portion  of  the  ilium  (Fig.  4,  No.  24).  The  scapula 
articulates  with  the  coracoid.  A  pneumatic  foramen  is  located  at 
the  base  of  the  acromion  process.  The  anterior  part  of  the  scapula 
is  provided  with  an  articular  head  and  is  provided  with  an  inner 
process,  called  the  processus  furcularis,  which  lies  near  the  f urcula 
and  coracoid.  An  outer  stronger  processus  humeralis  forms  the 


44  ANATOMY   OF    THE   DOMESTIC   FOWL 

posterior  half  of  the  glenoid  cavity,  or  camtas  glenoidalis ,  in  which 
the  humerus  articulates  and  the  processus  coracoideus. 

The  Clavicle.  Location. — The  clavicles,  commonly  known  as  the 
wish  bone,  are  located  in  the  anterior  chest  region. 

Description. — The  clavicles  are  long,  slender  bones  uniting  below 
in  the  hypocledium,  a  laterally  flattened  process.  They  are  joined 
to  the  upper  end  of  the  coracoid  by  fibrous  cartilage.  The  hypocle- 
dium is  joined  to  the  anterior  point  of  the  sternum  by  the  claviculo- 
sternal  ligament.  The  clavicles,  as  united  by  the  hypocledium, 
form  a  v-shaped  structure  called  the  furculum,  or,  popularly,  the 
wish  bone. 

The  forks  play  the  part  of  an  elastic  spring,  whose  office  it  is  to 
prevent  the  wings  from  coming  toward  each  other  during  con  traction 
of  the  depressor  muscles.  The  conformation  of  this  bone  is,  there- 
fore, like  the  sternum,  related  to  the  extent  and  power  of  flight; 
and  for  this  reason  it  is  that,  in  swift  flyers,  the  two  branches  of  the 
furculum  are  thick,  solid,  widely  separated,  and  curved  like  a  U; 
while  in  those  that  fly  heavily  and  with  difficulty,  these  branches  are 
thin  and  weak,  and  join  at  an  acute  angle.  The  latter  formation 
greatly  diminishes  its  strength,  and  lessens,  in  a  singular  manner, 
the  reactionary  power  of  the  bony  arch  it  represents. 

The  Coracoid.  Location. — The  coracoid  is  located  just  back  of 
the  clavicle  and  at  the  side  of  the  entrance  of  the  thoracic  cavity. 
It  is  the  strongest  bone  of  the  shoulder  girdle,  extending  upward, 
outward,  and  forward.  It  articulates  inferiorly  with  the  sternum 
and  superiorly  with  the  humerus  and  the  scapula,  and  is  attached 
to  the  superior  end  of  the  furcular  limb  by  a  fibrous  cartilage. 

Description. — It  is  thinnest  in  the  center  or  shaft  and  broadens 
toward  the  inferior  extremity.  The  upper  hook-like  part  of  the 
coracoid  forms  the  fore  part  of  the  glenoid  cavity,  and  together  with 
the  scapula  and  furcula  form  the  foramen  triosseum  through  which 
passes  the  tendon  of  the  elevator  muscle  of  the  wing.  The  upper 
end  flattens  out  into  three  tuberosities,  the  tuberositas  furcularis 
which  is  thick  and  to  which  attaches  the  limb  of  the  furcula,  the 
tuberositas  scapularis  which  unites  to  the  scapula,  and  the  tuberosi- 
tas humeralis  which  lies  between  these  and  articulates  with  the 
humerus. 

THE  FORE  LIMB 

The  bones  of  the  fore  limb  are  humerus,  ulna,  radius,  carpus, 
metacarpus,  arid  phalanges. 


OSTEOLOGY  45 

The  Humerus.    Location. — The  humerus  constitutes  the  arm, 
which,  when  at  rest,  lies  parallel  to  the  dorsal  vertebrae.     It  articu- 
lates superiorly  with  the  glenoid  cavity,  a  shallow  ball-and-socket 
joint,  formed  by  the  scapula  and  the  coracoid;  and  inferiorly  with  - 
the  ulna  and  radius. 

Description. — The  proximal  extremity  of  the  humerus  is  provided 
with  a  trochanter  (Fig.  n,  G,  No.  5)  and  a  large  oval  head  or  caput 
humeri,  which  articulates  in  the  glenoid  cavity.  The  head  is  an 
elongate,  semi-oval  convexity,  with  the  long  axis  transverse  from  the 
radial  to  the  ulnar  side  and  with  the  ends  continued  into  upper  and 
lower  crests.  The  upper  crest  of  the  head  of  the  humerus  is  on  the 
radial  side  and  the  lower  crest  on  the  under  side.  Under  this  latter 
crest  there  is  a  pneumatic  fossa  (Fig.  n,F,No.  i),  at  the  upper  end  of 
which  there  is  an  opening  into  the  bone,  the  pneumatic  foramen, 
which  brings  the  air-sac  into  communication  with  the  air  space 
of  the  bone.  The  shaft,  or  corpus  humeris,  is  irregularly  cylindrical 
and  slightly  S-shaped. 

The  proximal  part  of  the  shaft,  which  is  expanded  on  the 
palmar  side,  is  concave  across  and  convex  lengthwise.  The  dis- 
tal part  is  slightly  flattened.  The  shaft  of  the  humerus  is  almost 
cylindrical. 

The  distal  extremity  of  the  humerus  is  provided  with  two  articu- 
lar condyles,  one  of  which  articulates  with  the  ulna  and  the  other 
with  the  radius.  On  the  radial  side  of  the  palmar  surface  there  is 
a  ridge;  and  on  the  ulnar  side  of  the  same  surface  there  is  a  second 
ridge  diverging  to  the  opposite  tuberosity.  The  radial  surface  is 
a  narrow,  subelongate  convexity,  extending  from  the  middle,  ap- 
proximately, of  the  palmar  surface,  obliquely  to  the  lower  part  of  the 
radial  tuberosity.  The  two  articular  convexities,  or  trochlea,  at  the 
distal  end  of  the  humerus  are  bent  toward  the  palmar  aspect,  the 
anconal  aspect  is  the  side  on  which  the  elbow  is  situated.  The  inner 
convexity  is  the  larger  and  articulates  with  the  ulna.  To  the  out- 
side is  the  processus  cubitalis  humeri.  The  outer  articulates  with  the 
radius  and  is  so  arranged  that  the  radius  makes  a  greater  flexion  than 
the  ulna.  At  the  lower  end  of  the  humerus  there  is  a  depression 
which  receives  the  anconeus  of  the  ulna  during  flexion  and  extension 
of  the  forearm.  On  the  shoulder-  and  elbow-joint  are  found  grooves 
over  which  the  tendons  glide,  at  which  places  sheaths  are  provided. 
This  arrangement  also  aids  in  keeping  the  capsular  ligament  in 
place. 


46  ANATOMY   OF   THE   DOMESTIC   FOWL 

The  Ulna.  Location. — The  ulna,  larger  than  the  radius,  is  bent 
and  articulates  with  the  radius  only  at  the  ends.  The  two  bones 
are  bound  together  by  a  ligamentous  band.  It  also  articulates 
superiorly  with  the  distal  end  of  the  humerus,  and  inferiorly  with 
the  carpus.  When  the  wing  is  folded  the  radius  is  superior  and  a 
trifle  to  the  inner  side  of  the  ulna. 

Description. — The  proximal  end  is  most  expanded,  and  is  obliquely 
truncate  for  the  articular  excavation  adapted  to  the  ulnar  tubercle 
of  the  humerus.  A  short  angular  process  behind  the  cavity  repre- 
sents the  elecranon,  which  is  the  processus  olecranalis  coracoideus 
ulna  to  which  the  ligamentum  capsulare  cubiti  attaches.  On  the 
inner  side  of  the  head  is  the  internal  tubercle  of  the  ulna  and  on  the 
external  side  the  external  tubercle  of  the  ulna.  An  excavation  is 
noted  on  the  radial  side  of  the  proximal  end  for  the  lateral  articula- 
tion of  the  head  of  the  radius.  On  the  upper  side  near  the  articular 
part  is  located  the  sigmoid  cavity. 

The  shaft,  or  corpus  ulnae,  decreases  in  size  near  the  distal  end. 
It  is  slightly  curved,  flattened  laterally  with  an  internal  and  an  ex- 
ternal ridge. 

The  distal  end  of  the  ulna  is  slightly  expanded  into  a  trochlea 
which  is  sharply  convex  and  articulates  with  two  free  carpal  bones, 
the  scapho-lunar,  or  os  carpi  radiale,  and  the  cuneiform,  or  os  carpi 
ulnare.  The  scapho-lunar  is  placed  on  the  radial  side,  and  the  carpi- 
ulnare  on  the  ulnar  side.  The  distal  extremity  of  the  ulna  is  pro- 
vided with  a  styloid  process  and  on  the  dorsal  side  with  a  tubercle. 

The  Radius.  Location. — The  radius  lies  beside  the  ulna  with 
which  it  articulates  at  each  extremity.  At  the  inferior  extremity  the 
articulation  is  rotary.  It  also  articulates  superiorly  with  the  hu- 
merus and  inferiorly  with  the  os  carpi  radiale. 

Description. — The  radius,  cylindrical  in  shape,  is  more  slender 
than  the  ulna. 

The  proximal  end  is  expanded,  subelliptical,  with  a  concavity 
for  the  oblique  tubercle  and  a  thickened  convex  border  for  articu- 
lation with  the  ulna.  This  end  is  provided  with  the  tuberositas 
radii. 

The  shaft,  or  corpus  radii,  is  slender,  subcompressed,  and  has  a 
slight  bend  upward  from  the  ulna.  A  nutrient  foramen  occurs  in 
this  shaft. 

The  distal  end  is  expanded  and  rather  flattened  with  two  grooves 
on  the  anconal  side  for  passage  of  tendons.  For  articulation  with 


OSTEOLOGY  47 

the  scapho-lunar  the  radius  is  provided  with  a  terminal  transverse 
convexity  produced  palmad,  which  also  articulates  with  the  ulna 
laterally.  There  is  a  tuberosity  on  the  radial  side  of  the  expansion 
and  inferiorly  the  inferior  tuberculum  ossis  carpi  radialis  and  supe- 
riorly a  superior  tuberculum  ossis  carpi  radialis. 

The  Hand. — The  hand  is  made  up  of  the  carpus,  the  metacarpus, 
and  the  phalanges. 

The  bones  of  the  hand  are  so  arranged  as  to  allow  abduction  and 
adduction,  or  flexion  in  the  ulno-radial  plane,  movements  which  are 
necessary  in  the  outspreading  and  folding  of  the  wing.  Thus  the 
hand  of  the  fowl  moves  in  a  state  of  pronation,  without  the  power  of 
rotation.  The  carpal  bones  are  so  placed  between  the  anterior  arm 
and  metacarpus  as  to  reduce  the  abduction  which  is  necessary  to 
hold  and  extend  the  wing,  so  that  the  hand  or  wing  be  in  a  fixed 
position. 

The  Carpus. — The  carpus  in  the  domestic  fowl  is  represented  by 
two  bones,  ossa  carpi,  called  the  scapho-lunar,  or  os  carpi  radiale, 
and  the  cuneiform,  or  os  carpi  ulnare.  The  scapho-lunar  is  the 
smaller  and  is  located  between  the  radius  and  metacarpus.  The 
cuneiform  is  the  larger  and  is  located  between  the  ulna,  the  radius, 
and  the  metacarpus.  The  cuneiform  is  somewhat  anvil-like  in 
shape,  being  provided  with  a  body  and  two  prongs. 

The  Metacarpus. — The  metacarpal  bones,  or  ossa  metacarpi, 
two  in  number,  are  separated  at  their  middle  portion,  and  consoli- 
dated at  their  extremities.  The  upper  proximal  base  of  the  meta- 
carpus is  provided  with  a  tubercle,  the  tuberculum  muscularis,  and 
externally  the  tuberculum  ulnare  ossis  metacarpi.  The  distal  end 
of  the  metacarpal  bone  is  provided  with  a  tuberculum  articulare. 

The  Phalanges. — The  first  three  fingers  only  are  represented,  and 
these  are  rudimentary. 

The  first  finger  called  the  pollex  or  thumb,  consists  of  but  one 
joint.  It  is  located  on  the  proximal  and  outer  end  of  the  metacarpal 
bone.  It  has  on  its  proximal  end  a  tubercle,  the  tuberculum 
articulare. 

The  second  finger,  the  best  developed,  consists  of  two  phalanxes. 
These  are  the  main  bones  extending  from  the  metacarpus.  Each 
articular  end  is  provided  with  a  tuberculum  articulare. 

The  third  finger,  small,  cylindrical  in  shape,  is  located  at  the 
distal  and  inner  side  of  the  metacarpal  bone. 


48  ANATOMY   OF   THE  DOMESTIC  FOWL 

THE  PELVIC  GIRDLE  (Fig.  4,  No.  25;  Fig.  5,  Part  II,  6) 

The  pelvic  girdle  is  made  up  of  three  bones  as  follows:  the  ilium, 
the  ischium,  and  the  pubis,  all  of  which  are  fused  in  adult  life. 
They  are  separate  in  the  baby  chick  (Fig.  5,  Part  II,  6).  The  pelvis 
together  with  the  lumbo-sacral  vertebrae  forms  a  thin,  irregular, 
shell-like  structure  extending  superiorly  from  the  tail  to  the  thoracic 
region.  The  sacrum  is  broad  posteriorly  and  together  with  the 
ilium  forms  the  pelvic  roof.  The  ilium  and  ischium  are  its  lateral 
walls. 

The  top  surface  of  the  pelvis  shows  the  fovea  ilio-lumbalis  dorsalis, 
which  is  bounded  mesially  by  the  crista  ilii.  Between  it  and  the 
spina  lumbalis  there  is  a  broad  furrow,  the  bottom  of  which  is  formed 
by  the  dorsal  surface  of  the  lumbar  vertebrae.  The  sulcus  ilio- 
lumbalis  dorsalis  is  formed  by  the  rims  of  the  ilia,  so  that  a  ridge  is 
observable.  The  cavum  ilio-lumbale  dorsale  is  formed  by  the  iliac 
rims  on  either  side.  Anceriorly  is  the  canalis  ilio-lumbalis,  which  is 
formed  by  the  ilium  and  the  lumbar  vertebral  spines.  It  is  located 
longitudinally  to  the  vertebrae.  The  anterior  opening  of  this  canal 
is  the  larger.  Posterior  to  the  acetabulum  is  the  post-acetabular 
ridge. 

The  under  part  of  the  pelvis  presents  three  distinct  regions. 
The  cavity  is  divided  into  the  fovea  lumbalis,  or  anterior  part, 
the  fovea  ischiadica,  or  mesial  part,  and  the  fovea  pudendalis,  or 
posterior  part.  Posterior  to  these  is  the  region  called  the  planum 
coccygeum. 

The  fovea  lumbalis  contains  the  anterior  lobe  of  the  kidney, 
and  is  circumscribed  anteriorly  by  the  last  rib-carrying  vertebra, 
and  posteriorly  by  the  transverse  process  of  the  last  lumbar 
vertebra. 

In  the  fovea  ischiadica  which  follows,  lie  the  nerve  plexus 
ischiadicus  and  the  middle  lobe  of  the  kidney.  Its  posterior 
boundary  is  the  linea  arcuata.  The  linea  arcuata  is  a  line  drawn 
from  the  acetabulum  of  the  one  side  to  the  acetabulum  of  the  other 
side. 

The  fovea  pudendalis  contains  the  posterior  lobe  of  the  kidney. 
The  posterior  boundary  is  the  anterior  border  of  the  first  coccygeal 
vertebra.  It  gives  passage  to  the  nerve  plexus,  pudendo-hemor- 
rhoidalis. 

The  ilium,  the  ischium,  and  the  pubis  join  to  form  the  cotyloid 


OSTEOLOGY  49 

cavity,  or  acetabulum,  in  which  articulates  the  head  of  the  femur. 
The  floor  of  the  cavity  is  perforated  by  a  relatively  large  round 
foramen. 

The  Ilium.  Location. — The  ilium,  together  with  the  lumbo-sacral 
vertebrae,  forms  the  roof  of  the  pelvic  cavity.  It  articulates  at  its 
inner  border  with  the  lumbo-sacral  vertebrae,  postero-laterally  with 
the  ischium  and  at  the  cotyloid  cavity  with  the  pubis. 

Description. — The  ilium  is  remarkable  for  its  development 
in  the  long  axis  of  the  vertebral  column.  It  is  long  and 
narrow;  and  mesially,  where  it  is  thickest  it  forms  the  upper  wall 
of  the  acetabulum.  Anterior  to  the  acetabulum  it  is  outwardly 
concave,  and  posterior  to  the  acetabulum  it  is  convex.  The  ilium 
fuses  with  the  last  dorsal  vertebra  and  with  the  lumbo-sacral 
vertebrae  and  is  excavated  on  its  internal  face.  This  surface  is 
irregular  and  lodges  the  kidneys.  This  inner  margin  of  the  renal 
part  enters  with  the  square  extensions  of  the  posterior  excavation 
passing  into  the  posterior  iliac  spine.  The  external  margin  is  the 
extension  of  the  crista  transversa  and  forms  the  processus  ischiadicus. 
Posteriorward  the  renal  part  of  the  ilium  joins  the  ischium. 

The  ilia  converge  at  the  summits  of  the  anterior  sacral  spines 
forming  the  ilio-lumbar  spines. 

The  ilium  is  joined  to  the  square  extensions  of  the  last  sacral 
vertebra  by  the  symphysis  ilio-sacralis,  to  the  larger  part  of  the 
lumbar  vertebrae  by  the  sutura  ilio-lumbalis,  and  to  the  transverse 
processes  of  the  last  sacral  vertebrae  by  the  symphysis  ilio-sacri. 

The  Ischium.  Location. — The  ischium  is  located  in  the  postero- 
inferior  part  of  the  pelvis.  It  joins  superiorly  with  the  ilium,  and 
inferiorly  with  the  pubis. 

Description. — The  ischium  is  smaller  than  the  ilium  and  is  a 
flattened,  triangular-shaped  bone,  thickest  where  it  forms  the 
posterior  part  of  the  acetabulum,  becoming  thinner  and  broader  as 
it  extends  backward.  Posteriorly  it  forms  the  caudal  extension. 
The  inferior  border  is  turned  slightly  outward  and  is  fused  with  the 
pubis.  Between  these  bones  there  is  located  the  large  oval  ischiadic 
foramen,  through  which  passes  the  ischiadic  nerve.  This  bone  aids 
the  ilium  in  the  formation  of  the  obturator  foramen  through  which 
passes  the  tendon  of  the  internal  obturator  muscle.  The  lower 
part  of  the  ischium  which  separates  the  ischiadic  foramen  from  the 
obturator  foramen  is  called  the  ramus  ascendens  ossis  ischii. 


50  ANATOMY  OF   THE  DOMESTIC  FOWL 

The  Pubis.  Location. — The  pubis  is  located  along  the  inferior 
margin  of  the  ischium  and  extends  further  back  than  the  posterior 
border  of  the  ischium. 

Description. — The  pubis  is  a  long,  slender,  rib-like  bone.  It 
forms  the  lower  and  front  portion  of  the  acetabulum.  The  ischiadic 
foramen  formed  by  the  ischium'  and  pubis  is  single  and  nearly 
circular  in  fowls,  double  in  pigeons,  and  in  geese  and  ducks  it  is 
elongate. 

THE  HIND  LIMB  (Fig.  4,  Nos.  35,  47,  4»,  49,  5°,  5i,  52,  and  53;  Fig.  12) 

The  pelvic,  or  hind,  limb  supports  the  body.  The  bones  of 
each  leg  are  the  femur,  which  constitutes  the  thigh,  the  tibia  and 
the  fibula,  which  represents  the  leg,  and  the  metatarsus  and  the 
phalanges,  which  form  the  foot. 

The  Femur  (Fig.  12,  A  and  B).  Location. — The  femur,  or  os 
femoris,  the  first  bone  of  the  hind  extremity,  extends  obliquely 
downward  and  forward,  articulating  with  the  acetabulum  above 
and  the  tibia,  the  fibula,  and  the  patella  below. 

Description. — The  femur,  one  of  the  largest,  thickest,  and  strongest 
bones  of  the  body,  belongs  to  the  class  of  cylindrical  bones, 
and  presents  for  examination  a  shaft  and  two  extremities. 

The  superior,  or  proximal  extremity,  is  provided -with  a  head, 
caput  femoris;  the  neck,  collum  femoris;  and  the  trochanter.  The 
head  is  relatively  small,  and  is  marked  by  a  depression  above  for  the 
round  ligament  which  fills  the  cavity  in  the  acetabular  wall.  Its 
axis  is  nearly  at  right  angles  with  the  shaft.  A  neck  joins  it  to  the 
body  at  the  proximal  end.  External  to  the  head  of  the  femur  is 
the  trochanter.  The  trochanter  presents  an  outer  convexity  over 
which  the  tendon  of  the  gluteus  maximus  extends  to  become  inserted 
below.  The  trochanteric  ridge,  which  is  opposite  the  articular 
head,  presents  an  outer  flattened  surface  which  possesses  impressions 
for  muscular  attachments.  The  trochanteric  fossa,  or  fossa  tro- 
chanterica,  is  shallow. 

The  shaft,  or  corpus  femoris,  is  shorter  than  the  tibia,  is  in  general 
cylindrical,  bent  forward,  and  the  lower  half  is  flattened  and  ex- 
panded transversely.  A  nutrient  foramen  is  located  in  the  median 
portion  of  the  shaft.  The  shaft  shows  muscular  linear  ridges. 

The  distal  extremity  is  large  in  both  directions  and  comprises  the 
trochlea  in  front  and  two  condyles  behind,  one  internal  and  one  ex- 


OSTEOLOGY 


ternal.  The  condyles  are  separated  by  the  intercondyloid  fossa,  or 
fossa  inter condyloidea,  which  is  marked  with  pits  for  the  attachment 
of  ligaments;  and  above  this  is  the  epitrochlear  fossa. 


FIG.   12. — Bones  of  the  hind  extremity. 

A .  Posterior  view  of  femur. 

B.  Anterior  view.      I,  Shaft.     2,   Proximal  extremity.     3,   Distal  extremity. 
4,    Articular  head.     5,    Trochanter   major.     6,    Shallow  trochanteric  fossa.     7, 
Convexity  over  which  the  tendon  of  the  gluteus  maximus  glides.     8,  External 
condyle.     9,  Internal  condyle.      10,  Nutrient  foramen,      n,  Intercondyloid  fossa. 
12,  Muscular  linear  ridges.      13,  Epitrochlear  fossa. 

C.  Internal  view  of  tibia. 

D.  External  view,     i,    Shaft.     2,   Articular  head.     3,    Distal   end.     4,    The 
rotular  process.     5,  The  fibular  ridge.     6,  External  condyle.     7,  Internal  con- 
dyle.    8,  Intercondyloid  space.     9,  Nutrient  foramen. 

E.  Fibula,  lateral  view,     i,  Articular  head.     2,  Its  attenuated  portion. 

F.  Posterior  view  of  metatarsus,     i,  Trochlea  for  inner  or  second  digit.     2, 
Trochlea  for   middle   or  third  toe.     3,  Trochlea  for  outer  digit.     4,  Bony  core 
for    spur.     5,    Bony  canal  for  tendons.     6,  Groove  for  tendons.     7,  Fossa  inter- 
condyloidea. 

The  inner  condyle  begins  anteriorly  as  a  ridge,  and  expands  into 
a  convexity  which  attains  its  greatest  breadth  posteriorly  where  it 


52  ANATOMY   OF   THE   DOMESTIC   FOWL 

becomes  more  flattened.  The  inner  side  of  the  inner  condyle  is 
flattened  and  is  provided  with  a  tuberosity  at  its  mid-part  and  a 
second  just  above  the  posterior  part  of  the  condyle. 

The  outer  condyle  is  formed  in  the  same  manner  as  the  inner  con- 
dyle. It  is  indented  at  its  broad,  lower  end  by  an  angular  groove, 
which,  winding  divides  the  posterior  part  of  the  condyle  into  two 
convexities.  The  more  external  convex  ridge  and  the  groove  di- 
viding it  from  the  outer  condyle  are  adapted  to  the  head  of  the  fibula. 
There  is  in  this  part  afibular  ridge  and  above  this  ridge  a  tuberosity. 

The  Tibia.  Location. — The  tibia  (Fig.  12,  D  and  C)  extends  ob- 
liquely downward  and  backward  from  the  knee-joint  to  the  hock. 
It  articulates  above  with  the  femur  and,  by  its  procnemial  process 
with  the  patella,  below  with  the  metatarsus,  and  laterally  with  the 
fibula. 

Description. — The  tibia  is  the  longest  bone  in  the  posterior  limb, 
and  possesses  a  shaft  and  two  extremities.  It  is  largest  at  the  proxi- 
mal end  and  presents  three  faces. 

The  proximal  extremity  presents  a  semi-oval  articular  surface, 
not  quite  at  right  angles  with  the  shaft,  which  articulates  with  the 
condyles  of  the  femur.  The  margin  is  raised  toward  the  anterior 
of  the  bone.  The  head  of  the  tibia,  or  caput  tibia,  extends  into  a 
rotular  process  which  extends  transversely,  and  is  truncate.  From 
the  anterior  of  this  process  there  descends  two  vertical  ridges;  one 
near  the  angle  of  the  rotular  process,  the  procnemial  ridge;  the  other 
from  the  outer  fibular  angle,  the  ectocnemial  ridge.  On  the  outer  side 
of  the  intercondylar  tuberosity  there  is  a  surface  for  the  ligamentous 
union  with  the  head  of  the  fibula;  and  a  short  distance  below  this 
there  is  a  vertical  ridge  for  the  close  attachment,  almost  a  fusion, 
with  the  fibula,  called  the  fibular  ridge. 

The  shaft,  or  corpus  tibia  is  straight  and  the  upper  two-thirds 
subtrihedral;  the  lower  third  oval.  A  nutrient  foramen  occurs  near 
the  upper  postero-internal  portion  of  the  middle  third  of  the 
bone. 

The  distal  extremity  is  much  smaller  than  the  proximal  one; 
it  is  quadrangular  in  form.  The  expanded  inferior  end  of  the  tibia 
forms  two  articular  condyles  above  which  posteriorly  there  is  the 
epicondyloid  fossa.  The  inner  condyle,  the  larger,  has  a  groove  near 
the  lower  end  of  the  anterior  part  of  the  shaft,  which  deepens  to- 
ward the  intercondyloid  space.  This  intercondyloid  fossa  in  young 
birds  is  covered  by  a  strong  ligament,  which  in  older  birds,  becomes 


OSTEOLOGY  '  .      .     .  53 

ossified.  On  the  lateral  side  of  each  condyle,  there  is  a  depression 
for  the  attachment  of  ligaments. 

The  Patella.  Location. — The  patella,  or  knee-cap,  thin  and  wide, 
articulates  with  the  procnemial  process  of  the  tibia,  and  with,  the 
deep  trochlea  of  the  distal  end  of  the  femur. 

Description. — The  patella  is  irregular  in  shape  with  three  faces 
and  three  borders.  The  posterior  surface  is  articular.  The  other 
two  surfaces  are  rough  for  tendinous  attachment.  The  patellar 
ligaments  in  old  birds  may  become  ossified. 

In  order  to  turn  the  foot  in  and  out,  the  tibia  not  only  turns 
around  the  inner  condyle  of  the  femur,  but  also  around  the  patella, 
so  that  the  posterior  surface  turns  outward  and  thus  turns  outward 
the  metatarsus  and  all  the  toes. 

The  Fibula.  Location.— The  fibula  lies  at  the  outer  border  of  the 
tibia.  It  articulates  superiorly  with  the  outer  condyle  of  the  femur, 
and  laterally  with  the  tibia. 

Description.— The  fibula  is  rudimentary;  it  is  largest  superiorly  and 
tapers  to  a  slender  point.  The  head  is  compressed  laterally,  and  fur- 
nishes an  upper  and  an  inner  articular  surface. 

The  Tarsus. — There  exist,  during  fetal  development  of  the  chick, 
two  rows  of  tarsal  bones  which  later  become  fused.  The  upper 
row  fuses  with  the  tibia  and  the  lower  with  the  metatarsus.  There- 
fore, in  the  adult,  there  is  no  tarsus. 

The  Metatarsus.  Location. — The  metatarsal  bone  extends  down- 
ward and  forward.  In  birds  it  consists  of  one  bone,  which  ar- 
ticulates superiorly  with  the  inferior  extremity  of  the  tibia.  On  the 
distal  end  it  has  a  threefold  trochlear  arrangement  which  articulates 
with  the  three  principal  digits. 

Description. — The  proximal  extremity  posteriorly  has  a  process 
which  may  be  considered  as  a  consolidation  of  originally  separate 
metatarsal  bones.  The  process  at  the  supero-posterior  part  of 
the  metatarsus  is  called  the  hypotarsus  of  the  tarso-metatarsus, 
through  which  extends  a  canal  called  the  hypotarsal  canal,  and  which 
gives  passage  to  flexor  tendons. 

The  proximal  end  of  the  metatarsus  is  ossified  from  one  center  of 
ossification  forming  an  epiphysis  which  caps  the  ends  of  the  three 
original  metatarsal  bones  that  coalesce,  first  with  one  another,  then 
with  the  epiphysis,  thus  forming  a  single  compound  bone.  Above 
and  just  to  the  inside  of  the  metatarsus  there  may  occur  a  small 
bone  which  is  imbedded  in  ligaments  and  articulates  with  the 


54  ANATOMY   OF   THE   DOMESTIC   FOWL 

inner  proximal  surface  of  the  metatarsus.     This  has  been  called 
by  Gadow  a  sesamoid  bone. 

The  shaft  shows  tendonal  grooves  which  are  best  marked  on  the 
posterior  surface.  The  shaft  is  rounded  at  the  sides  and  flattened 
on  the  anterior  and  posterior  surfaces.  At  the  juncture  of  the 
middle  and  inferior  thirds  of  the  metatarsus  there  is  a  conical  process 
turned  slightly  backward,  which  serves  as  a  base  for  the  spur.  The 
spur  is  a  horny  structure. 

At  the  distal  extremity  occurs  the  threefold  trochlear  arrangement 
mentioned  above,  which  incloses  the  fossa  intercondyloidea.  The 
inner  trochlea  is  the  broadest,  and  the  outer  the  narrowest.  The 
inner  trochlea  articulates  with  the  proximal  end  of  the  second,  the 
middle  with  the  third,  and  the  outer  with  the  fourth  toe. 

The  Phalanges.  Location. — Most  domestic  fowls  are  provided 
with  four  digits,  or  toes;  the  Houdan  and  Dorking  are  provided  with 
five.  In  fowls  with  four  toes  the  three  principal  toes,  the  second,  the 
third,  and  the  fourth,  are  directed  forward,  and  the  first,  or  hallux, 
is  directed  backward. 

Description. — The  last  phalanx  of  each  toe,  called  the  ungual 
phalanx,  is  slightly  curved  downward,  is  pointed  anteriorly,  like 
the  claw  of  the  cat  or  dog,  and -is  covered  with  a  horny  sheath.  The 
articular  ends  of  the  joints  of  the  phalanges  are  enlarged.  Tbe  base 
of  the  basal  phalanx  has  two  enlargements,  the  superior-inferior 
tubercles,  or  tuberculum  superius  et  inferius,  between  which  is  lo- 
cated the  fossa  articularis  transversa.  Laterally  the  head  has  two 
condyles,  condyli  laterales,  which  are  divided  by  the  sulcus  longi- 
tudinalis.  The  bodies  of  the  phalanges  vary  in  form;  they  are  supe- 
riorly rounded,  but  inferiorly  rounded,  flat,  or  even  somewhat  con- 
cave. The  distal  extremity  has  an  articular  trochlea. 

The  first  toe,  or  digit,  called  the  great  toe,  or  hallux,  is  composed 
of  three  phalanges,  or  segments.  The  first  segment,  or  basal 
phalanx  is  considered  a  rudimentary  metacarpal  bone;  it  is  at- 
tached by  a  fibrous  cartilaginous  tissue  to  the  inner  posterior 
surface  of  the  inferior  extremity  of  the  metacarpal  bone  just  be- 
low the  spur. 

The  second  toe,  likewise  composed  of  three  phalanges,  is  directed 
forward.  It  articulates  with  the  inner  trochlea  located  on  the 
inferior  metacarpal  bone. 

The  third  toe,  made  up 'of  four  phalanges,  is  the  middle  of  the 


OSTEOLOGY  55 

three  forward  toes.     It  articulates  with  the  middle  trochlea  of  the 
inferior  extremity  of  the  metacarpal  bone. 

The  fourth  toe,  is  composed  of  five  phalanges;  it  is,  however, 
of  approximately  the  same  length  as  the  third,  the  segments  being- 
shorter.     The  fourth  or  outer  toe  articulates  with  the  outer  trochlea 
of  the  distal  extremity  of  the  metacarpal  bone. 


ARTHROLOGY 

Kinds  of  Joints. — Joints  may  be  movable,  immovable,  or  mixed. 
In  movable,  or  true  joints  the  articular  surface  of  each  bone  is  covered 
by  cartilage.  The  bones  are  held  together  by  ligaments,  the 
capsular  one  often  surrounding  the  joint  and  enclosing  the  synovial 
membrane.  In  some  joints  there  is  a  pad  of  fibrous  cartilage 
interposed  between  the  two  articular  cartilages.  Such  a  pad, 
called  a  meniscus,  adds  to  the  elasticity  and  the  free  movement 
of  the  joint.  Movable  joints  form  the  most  numerous  class;  they 
are  for  the  most  part  found  in  the  limbs. 

In  an  immovable  joint  there  is  only  a  thin  layer  of  fibrous  or 
cartilaginous  material  interposed  between  the  bones.  The  fibrous 
layer  of  the  periosteum  of  both  bones  unite  to  cover  the  connecting 
material  and  becomes  attached  to  the  same,  thus  serving  as  a  liga- 
ment. If  the  connecting  material  is  fibrous,  the  joint  is  called  a 
suture;  if  cartilaginous,  a  synchondrosis.  These  joints  are  found 
in  the  skull  and  in  the  pelvis. 

The  term  mixed  is  used  with  reference,  not  to  the  motion  in  joints, 
but  to  their  structure,  which  partakes  of  the  nature  of  both  the 
movable  and  immovable.  The  bones  are  firmly  joined  by  a  strong 
interposed  pad  of  fibrous  cartilage  to  which  also  is  adherent  the 
ligaments  of  the  joint.  There  are  no  capsular  ligaments;  the 
cartilaginous  pad  or  disc  is  softer  toward  its  center,  where  occasion- 
ally there  may  be  one,  or  even  two,  narrow  cavities.  Authorities 
differ  as  to  whether  such  cavities  are  lined  by  synovial  membrane 
or  not.  Since  there  are  really  no  frictional  surfaces  in  such  a  joint, 
motion  depends  upon  the  flexibility  of  the  disc.  The  joints  between 
the  vertebral  centra  afford  the  best  illustration  of  the  mixed  class. 

Movement  of  Joints. — The  movements  admissible  in  joints  may 
be  divided  into  four  kinds:  gliding,  angular  movement,  circumduc- 
tion,  and  rotation.  These  movements  are  often,  however,  more  or 
less  combined  in  the  various  joints.  It  is  seldom  that  there  occurs 
only  one  kind  of  motion  in  any  particular  joint. 
Gliding  movement  is  the  most  simple  kind  of  motion  that  can 

56 


ARTHROLOGY  57 

take  place  in  a  joint,  one  surface  gliding  or  moving  over  another 
without  any  angular  or  rotary  movement. 

Angular  movement  occurs  only  between  the  long  bones.  By 
it  the  angle  between  the  two  bones  is  increased  or  diminished^  -It 
may  take  place  in  four  directions:  forward  and  backward,  consisting 
of  flexion  and  extension;  or  inward  and  outward  from  the  medial 
line  of  the  body,  consisting  of  adduction  and  abduction.  Abduction 
of  a  limb  is  movement  away  from  the  medial  line  of  the  body. 
Adduction  of  a  limb  is  movement  toward  the  medial  line  of  the  body. 

Circumduclion  is  that  limited  degree  of  motion  which  takes 
place  between  the  head  of  a  bone  and  its  articular  cavity,  whilst 
the  extremity  and  sides  of  the  limb  are  made  to  circumscribe  a 
conical  space,  the  base  of  which  corresponds  with  the  inferior 
extremity  of  the  limb,  the  apex  with  the  articular  cavity;  this 
kind  of  motion  is  best  seen  in  the  shoulder-  and  hip-joint. 

Rotation  is  the  movement  of  a  bone  upon  an  axis,  which  is  the 
axis  of  the  pivot  on  which  the  bone  turns,  as  in  the  articulation 
between  the  atlas  and  axis,  when  the  odontoid  process  serves  as  a 
pivot  around  which  the  atlas  turns;  or  else  is  the  axis  of  a  pivot- 
like  process  which  turns  within  a  ring,  as  in  the  rotation  of  the  radius 
upon  the  humerus. 

Pronation  is  a  form  of  rotation  in  which  the  inferior  extremity 
of  the  radius  passes  before  the  ulna,  and  thus  causes  the  hand  to 
execute  a  kind  of  rotation  from  without  inward. 

Supination  is  a  form  of  rotation  in  which  the  movement  of  the 
forearm  and  hand  are  carried  outward  so  that  the  anterior  surface 
of  the  latter  becomes  superior. 

The  Ligamentous  Structure. — Ligaments  are  dense,  fibrous,  con- 
necting structures.  They  are  made  up  principally  of  white  fibrous 
tissue  and  exist  in  all  true  joints. 

There  are  four  kinds  of  ligaments  associated  with  true  joints: 

The  first  kind,  the  capsular  ligament  which  encloses  all  true 
joints,  is  thin  and  consists  of  interlaced  fibers  attached  to  the  bone 
at  the  edges  of  the  articular  cartilages.  It  either  partly  or  wholly 
surrounds  the  joint,  enclosing  and  protecting  a  synovial  apparatus, 
which,  by  secreting  a  liquid  resembling  serum,  lubricates  the  joint 
to  prevent  friction. 

The  second  kind,  the  binding  or  lateral  ligaments,  consist  of 
flattened  or  rounded  cords  or  bands  of  fibrous  tissue.  Such  a 
ligament  extends  from  one  bone  to  the  other,  and  firmly  attached  to 


58  ANATOMY   OF    THE   DOMESTIC   FOWL 

their  roughened  surfaces,  holds  the  bones  in  place  and  at  the  same 
time  allows  the  required  amount  of  motion. 

The  third  kind,  located  between  the  joints,  is  called  interosseous 
ligament. 

The  fourth  kind,  called  the  annular  ligament  binds  down  and 
protects  the  tendons. 

Ligaments  of  the  Ear1. — The  concha  of  the  ear  is  provided  with 
a  superior  and  an  inferior  ligament. 

Ligaments  of  the  Jaw. — The  articulations  of  the  lower  jaw  are 
complex.  The  freely  movable  articulation  is  between  the  inferior 
maxilla  and  the  quadrate.  Less  freely  movable  articulations  are 
formed  by  the  quadrate  with  the  temporal,  the  zygomatic  and  the 
pterygoid.  A  lateral  ligament  of  the  jaw,  the  articulo-jugale  ex- 
tends from  the  posterior  border  of  the  inner  wing  of  the  os  articulare 
of  the  inferior  maxilla  (Fig.  8,  No.  ir,  and  Fig.  19,  No.  15)  to  the 
outer  border  of  the  os  quadrate  jugulare. 

A  lateral  temporo-maxillary  ligament  extends  from  the  outer  sur- 
face of  the  temporal  bone  to  the  outer  border  of  the  os  articulare 
of  the  inferior  maxilla  (Fig.  8,  No.  n,  and  Fig.  19,  No.  14). 

Ligaments  of  the  Vertebrae. — In  each  space  between  the  bodies 
of  the  vertebrae  there  is  a  meniscus  intervertebralis.  This  meniscus 
is  analogous  to  the  annulus  fibrosus  of  mammals  (Gadow),  which, 
is  possibly  formed  as  a  protrusion  of  the  anterior  surface  of  the  ver- 
tebral body.  The  meniscus  or  disc  may  develop  into  a  ring-shaped 
structure,  the  true  meniscus,  or  it  may  develop  to  different  degrees 
as  an  extension  of  the  vertebral  body  surface,  and  become,  as  in  the 
dorsal  and  lumbar  regions,  fused  with  the  vertebral  segments,  in 
which  case  it  is  called  the  annulus  fibrosus. 

The  vertebral  disc  which  is  connected  with  the  atlas  and  which 
is  fused  with  that  bone,  represents  the  first  meniscus,  which  is  called 
the  ligamentum  transversum  atlantis.  This,  as  well  as  other  ligaments 
of  the  spinal  column,  may  become  ossified. 

The  ligament  which  is  located  between  those  vertebral  bodies 
which  face  each  other  and  is  inside  the  joint  cavity,  is  called  the 
ligamentum  suspensroium  corporum  -vertebralium.  It  passes  through 
the  central  opening  of  the  meniscus  and  lies  exactly  in  the  long  axis 
of  the  body  of  the  vertebra. 

The  first  ligament  of  the  neck  is  the  ligamentum  suspensorium 
dentis  epistrophei.  The  ligamentum  capsulare  atlantico-occipitale 

1  The  classification  of  Gadow  is  used. 


ARTHROLOGY  59 

and  the  ligamentum  capsulare  atlantico-epistrophicum  odontoideum 
are  two  parts  of  the  joint  capsule  of  the  vertebral  body.  Other 
ligaments  of  this  part  are  the  membranes  obturatoria  inter-vertebrates 
posteriores,  which  are  located  between  the  semicircular  rims  of  the 
neck  vertebrae. 

The  ligamentum  transversum  atlantis  surrounds  the  occipital 
condyle. 

The  ligamentum  nuchce  is  a  thin,  membranous,  ribbon-like  struc- 
ture which  lies  between  the  muscles  of  the  right  and  those  of  the 
left  side  of  the  middle,  and  the  lower  part  on  the  posterior  of  the  neck, 
and  ends  in  attachments  to  the  superior  spines  of  the  cervical 
vertebrae. 

The  ligamentum  elasticum  interspinale  profundum  and  the  liga- 
mentum elasticum  interspinale  superficiale  and  the  three  last  named 
are  the  ligaments  which  keep  the  neck  of  the  fowl  in  the  s-shape, 
without  the  action  of  the  muscles. 

The  ligamentum  capsulare  obliquum  connects  the  facets  of  the 
oblique  processes. 

Ligaments  of  the  Ribs. — The  thick  inferior  end  of  the  sternal  por- 
tion of  the  true  rib  has  two  small  articular  heads,  which  articulate 
with  two  depressions  in  the  articular  surface  of  the  sternum.  This 
articulation  is  held  firm  by  a  capsular  ligament. 

'  The  upper  end  of  the  sternal  rib  forms  an  almost  perfect  right  angle 
with  the  inferior  end  of  the  dorsal  rib  with  which  it  is  connected  by  a 
joint  provided  with  a  synovial  apparatus  and  a  capsular  ligament. 
This  arrangement  allows  free  movement  Outward  and  inward  and  is 
the  main  joint  in  respiration. 

The  upper  end  of  the  dorsal  portion  of  the  rib  articulates  with  the 
dorsal  vertebra.  The  joint  formed  by  the  articular  head  with  the 
body  of  the  vertebra  is  provided  with  a  capsular  ligament.  The 
tubercle  of  the  rib  articulates  with  the  facet  on  the  transverse  proc- 
ess of  the  dorsal  vertebra,  and  is  provided  with  a  transverse  liga- 
ment, called  the  ligamentum  transfer  sum  externum.  It  is  also  pro- 
vided with  a  capsular  ligament. 

The  ligamentum  triangulare  connects  each  processus  uncinatus 
with  the  succeeding  rib.  This  ligament  is  in  the  form  of  a  membra- 
nous sheet,  or  aponeurosis. 

Ligaments  of  the  Sternum  (Fig.  13). — The  external  and  the  in- 
ternal notches  of  the  sternum  are  bridged  over  with  a  thin  membrane 


60  ANATOMY   OF   THE  DOMESTIC  FOWL 

which  gives  an  extensive  surface  for  muscular  attachments.     The 
sternal  muscles  overlie  this  portion. 


FIG.  13. — Muscles  of  the  fore  extremity.  Inside  view,  i,  Lateral  external 
process  of  sternum.  2,  Lateral  internal  process  of  same.  3,  Ligament  of  the 
external  notch.  4,  Ligament  of  the  internal  notch.  5,  Pectoralis  major.  50, 
Its  fan-shaped  expansion  at  shoulder-joint  laid  back.  6,  Pectoralis  tertius.  7, 
The  coracoid.  8,  Biceps.  8a,  Its  long  head.  8b,  Its  short  head.  9,  Pectoralis 
secundus.  10,  Rectus  abdominis.  n,  Teres  et  infraspinatus.  12,  Deltoid. 
13,  Capsular  ligament.  14,  Teres  minor.  15,  Coraco-brachialis.  16,  Serratus 
magnus  anticus.  17,  Extensor  metacarpi  radialis  longior.  i8,'Pronator  brevis. 
19,  Flexor  carpi  ulnaris.  20,  Flexor  carpi  ulnaris  brevior.  21,  Flexor  digitorum 
profundus.  22,  Extensor  indicis  longus.  23,  Extensor  ossis  metacarpi  pollicis. 
24,  Humerus.  25,  Shoulder.  26,  Elbow.  27,  Carpus.  28,  Section  through 
vertebra.  29,  Keel  of  sternum.  28a,  Flexor  brevis  pollicis.  290,  Extensor 
proprius  pollicis.  30,  Flexor  minimi  digiti  brevis.  31,  Interosseous  palmaris. 
32,  Interosseous  palmaris. 

The  sternum  is  connected  by  a  fibrous  mass  with  the  inferior 
portion  of  the  clavicle,  or  hypocledium  (Fig.  57),  the  damculo  sternal 
ligament. 

The  inferior  narrow  elongated  end  of  the  coracoid  forms  with  the 
sternum  a  true  articulation,  which  is  provided  with  a  capsular 


ARTHROLOGY  6 1 

ligament,  the  ligamentum  capsulare.     Capsular  ligaments  occur  at 
the  articulations  between  the  sternum  and  ribs. 

Ligaments  of  the  Shoulder-joint  (Fig.  13). — The  shoulder-joint 
is  made  up  of  the  scapula,  the  humerus,  and  the  coracoid.  The  ends 
of  these  three  bones  form  the  foramen  triosseum  (Fig.  15,  No.  A,  7) 
through  which  passes  the  tendon  of  the  elevator  muscle  of  the  wing. 

The  f  urcula,  independent  of  the  shoulder-joint  or  girdle,  is  attached 
to  the  supero-internal  part  of  the  proximal  end  of  the  coracoid  by 
fibrous  connective  tissue;  it  is  also  connected  to  the  other  bones  of 
the  shoulder-joint  by  the  ligamentum  coraco-furculare  and  the 
ligamentum  furculo-scapulare. 

The  ligamentum  coraco-scapulare  extends  from  the  tuberosity  of 
the  f  urcula  to  the  coracoid  and  to  the  processus  furcularis  of  the 
scapula. 

The  ligamentum  coracoido-scapulare  externum  extends  between 
the  external  tuberosity  of  the  coracoid,  the  tuberosity  of  the  scapula, 
and  the  humerus. 

The  ligamentum  coracoideo-scapulare  inferius  extends  from  the 
coracoid  to  the  inner  tubercle  of  the  scapula. 

Another  long,  broad  ligament  belongs  to  the  episternal  apparatus. 

The  shoulder-joint  is  provided  with  a  wide,  loose,  capsular  liga- 
ment (Fig.  13,  No.  13).  Attached  to  the  humerus  are  four  other 
ligaments,  of  which  three  pass  from  the  anterior  end  of  the  coracoid 
and  the  fourth  from  the  scapula.  The  latter  are  as  follows:  first,  the 
super o-anlerior  ligamentum  humero-coracoideum,  which  extends  from 
the  small  tubercle  of  the  humerus  to  the  coracoid  bone;  second,  the 
antero-inferior  ligamentum  humero-coracoideum,  which  extends  from 
the  humerus  to  the  coracoid,  third,  the  ligamentum  coraco-humerale, 
which  extends  from  the  coracoid  to  the  large  tubercle  of  the  humerus; 
fourth,  the  ligamentum  humero-scapulare  which  extends  between  the 
processus  humeralis  of  the  scapula  and  the  head  of  the  humerus. 

Ligaments  of  the  Elbow- joint  (Fig.  14).— The  elbow- joint  is  made 
up  of  the  ulna,  radius  and  the  humerus.  The  ligaments  of  the  elbow- 
joint  are  as  follows:  the  ligamentum  capsulare  cubiti,  or  capsular 
ligament,  which  extends  from  the  processus  cubitalis  of  the  humerus 
to  the  processus  olecranalis  coracoideus  of  the  ulna  and  to  the  tuber- 
ositas  radii  of  the  radius  (Fig.  15,  No  5). 

The  ligamentum  later  ale  cubiti  externum  connects  the  outer  hu- 
meral distal  extremity  with  the  head  of  the  radius  (Fig.  15,  No.  2). 

The  ligamentum  laterale  cubiti  internum  lies  between  the  inner 


62 


ANATOMY   OF   THE   DOMESTIC   FOWL 


distal  extremity  of  the  humerus  and  the  tuberculum  internum  of 
the  ulna  (Fig.  14,  No.  9). 

The  ligamentum  annulare  radii  originates  on  the  olecranon,  sur- 
rounds the  head  of  the  radius,  and  is  attached  to  the  tuberculum 
internum  of  the  ulna  (Fig.  15,  No.  3). 

The  ligamentum  cubiti  teres  extends  from  the  head  of  the  radius 
to  the  upper  end  of  the  ulna  (Fig.  15,  No.  4). 


FIG.  14. — Muscles  and  ligaments  of  the  arm  and  forearm  of  a  hen. 

A.  External  view,     i,  Expansor  secundarium.     2,  Tensor  patagii  longus.     3, 
Tensor  patagii  brevis.     5,  Brachialis  anticus.     6,  Pronator  longus.     7,  Supinator 
brevis.     8,  Extensor  indicis  brevis.     10,  Scapulo-humeralis. 

B.  Internal  view.     9,  Ligamentum  laterale  cubiti  internum. 


The  ligamentum  transversum  spreads  out  between  the  head  of  the 
ulna  and  the  radius,  thus  uniting  the  two  bones,  and  limiting  supina- 
tion  (Fig.  15,  No.  i). 

Ligaments  of  the  Carpal  Joint. — The  carpal  joint  is  made  up  of 
the  ulna,  radius,  the  two  carpal  bones  and  the  metacarpus.  . 

There  are  two  strong  ligamenta  obliqua  carpi  ulnaris  which  ex- 


ARTHROLOGY 


tend  from  the  processus  styloideus  of  the  ulna  to  the  tuberculum 
posterius  carpi  ulnaris  of  the  os  carpi  ulnaris. 

The  ligamentum  posticum  ulnare  carpi  ulnaris  extends  from  the 
processus  styloideus  of  the  ulna  to  the  os  carpi  ulnaris. 


] 


FIG.   15. — Ligaments  of  the  arm  and  forearm  of  a  hen. 

A.  The  scapulo-coraco-humeral  articulation,     i.  Proximal  end  of  the  humerus. 

2,  Articular  head  of  humerus.     3,  The  coracoid.     4,  Proximal  end  of  the  clavicle. 
5,  Tendon  of  pectoralis  tertius.     6,  Tendon  of  pectoralis  secundus.     7,  Opening 
or  foramen  triossium  through  which  the  tendon  of  the  elevator  of  the  wing 
passes.     (Pectoralis  secundus.     8,  Broken  end  of  scapula. 

B.  i,  Ligamentum  transversum.     2,  Ligamentum  laterale  cubiti  externum. 

3,  Ligamentum  annulare  radii.     4,  Ligamentum  cubiti  teres.     5,  A  portion  of 
the  ligamentum   capsulare   cubiti.     6,  Distal  extremity  of  humerus.     7,  Ulna. 
8,  Radius. 

C.  Muscles  of  the  outside  surface  of  the  arm.     i,  Tensor  patagii  longus.     2, 
Extensor  digitorum  communis.     3,  Tensor  patagii   brevis.     4,   Anconeus.     5, 
Plexor  carpi  ulnaris.     6,  Biceps.     7,  Triceps.     8.  Deltoid.     9,  Brachialis  anticus. 
10,  Flexor  metacarpi  radialis.     n,  Extensor  ossis  metacarpi  pollicis.     12,  Ex- 
tensor metacarpi  radialis  longior.     13,  Extensor  indicis  longus. 

The  ligamentum  ulnare  carpi  radialis  is  a  short  ribbon-like  ligament 
which  passes  over  the  above-mentioned  ligaments  and  is  attached 
to  the  inner  surface  of  the  os  carpus  radialis. 

The  ligamentum  ulnare  carpi  radialis  internum  is  a  strong  ligament 


64  ANATOMY   OF   THE  DOMESTIC  FOWL 

which  originates  on  the  inner  part  of  the  elbow.     It  extends  to  the 
upper  rim  of  the  base  of  the  main  digit. 

The  ligamentum  radiate  carpi  radialis  externum  originates  on  the 
outside  of  the  head  of  the  middle  digit  and  inserts  to  the  superior 
tuberculum  carpi  radialis  of  the  radius. 

The  ligamentum  carpi  radialis  internum,  a  short  ligament,  extends 
from  the  inside  of  the  head  of  the  main  digit  to  the  inner  rim  of  the 
carpi  radialis. 

The  ligamentum  carpi  interosseum  is  located  between  the  carpal 
bones. 

The  ligamentum  ulnare  metacarpi  internum  is  spread  out  between 
the  processus  styloideus  of  the  ulna  and  the  tuberositas  muscularis 
on  the  upper  side  of  the  middle  finger  base  at  a  point  where  the 
second  and  the  third  metacarpi  separate. 

The  ligamentum  ulnare  metacarpi  externum  extends  from  the 
tubercle  of  the  distal  extremity  of  the  ulna,  on  the  dorsal  side, 
to  the  tubercle  on  the  base  of  the  metacarpus. 

Ligamentum  radiate  metacarpi  extends  from  the  head  of  the  inner 
digit  to  a  point  near  the  tuberculum  muscularis  of  the  radius. 

The  ligamentum  transversum  ossis  carpi  radialis  et  metacarpi  is 
located  between  the  inferior  tuberculum  ossis  carpi  radialis  and  the 
first  metacarpal  bone. 

There  is  another  ligament  between  the  tuberculum  superiorus 
carpi  radialis  and  the  first  metacarpal  bone. 

The  ligamentum  ossis  carpi  radialis  internum  et  metacarpi  extends 
from  the  inner  surface  of  the  carpus  radialis  to  the  tuberositas  mus- 
cularis of  the  radius. 

The  ligamentum  ossis  carpi  ulnaris  externum  et  metacarpi  extends 
from  the  ulnar  carpal  bone  to  the  tuberculum  of  the  metacarpal  bone. 

The  ligamentum  ossis  carpi  ulnaris  internum  et  metacarpi  extends 
from  the  processus  uncinatus  of  the  ulnar  carpal  bone  to  the  tuber- 
ositas muscularis  of  the  metacarpal  bone. 

Ligaments  of  the  Finger. — The  ligamentum  pollicare  connects  the 
thumb  with  the  first  metacarpal  bone. 

The  ligamentum  anterius  ossis  metacarpi  et  primes  phalangis 
digiti  secundi  extends  from  the  tuberculum  articulare  metacarpi,  of 
the  proximal  end  of  the  metacarpus,  to  the  tuberculum  articulare  of 
the  first  phalanx  of  the  second  or  large  finger.  Similarly  attached, 
are  also  an  internal  and  a  posterior  ligament,  or  ligamentum  internum 
and  ligamentum  posterius. 


ARTHROLOGY  65 

The  three  phalanges  are  all  provided  with  capsular  ligaments,  or 
ligamenta  capsularia,  which  bind  together  the  several  phalanges. 

The  small  or  third  finger  is  connected  to  the  metacarpus  by  a 
capsular  ligament,  the  ligamentum  capsulare,  and  by  an  interosseous 
ligament,  or  ligamentum  interosseum  digitorum,  to  the  first  phalanx 
of  the  second  finger. 

Ligaments  of  the  Pelvis. — The  obturator  foramen,  formed  by  the 
ilium  and  the  ischium,  is  covered  by  a  broad  membranous  ligament 
(Fig.  4,  No.  29). 

The  oblong  foramen,  or  foramen  oblongum,  and  the  foramen 
ischiadicum,  formed  by  the  ischium  and  the  pubis  are  covered  by 
broad  membranous  ligaments  (Fig.  4,  Nos.  29  and  60). 

Poupartfs  ligament  or  ligamentum  Poupartii,  quite  small  in  fowls, 
extends  from  the  anterior  lower  rim  of  the  ilium  to  the  pelvic  cavity, 
and  is  inserted  at  the  bottom  of  the  acetabulum. 

Another  broad  ligament  originates  from  the  posterior  rim  of  the 
ischium  and  is  attached  to  the  square  surface  of  the  first  coccygeal 
vertebra. 

The  ilio-pubic  ligament  extends  from  the  pubic  spine  to  the  last 
rudimentary  rib. 

Ligaments  of  the  Hip-joint  (Fig.  25,  F). — The  hip- joint  is  made  up 
of  the  ilium,  ischium,  pubis  and  femur  and  is  a  deep  ball-and-socket 
joint.  The  cavity  or  acetabulum  is  called  a  cotyloid  cavity. 

The  hip- joint  is  provided  with  three  ligaments. 

The  ligamentum  capsulare  femoris  is  attached  around  the  rim  of 
the  cotyloid  cavity  and  around  the  rim  of  the  articular  head  of  the 
femur  (Fig.  25,  No.  F,  4). 

The  ligamentum  teres,  or  round  ligament,  is  a  very  short  ligament 
which  closes  the  hole  at  the  floor  of  the  cotyloid  cavity,  at  which 
point  it  is  attached.  It  is  also  attached  to  the  head  of  the 
femur. 

The  ligamentum  ilio-sacrale  strengthens  the  hip-joint  capsule. 
It  passes  from  the  lower  anterior  rim  of  the  os  ilii,  extending  over  the 
capsule  to  the  neck  of  the  femur  to  which  it  is  attached. 

The  Ligaments  of  the  Knee-joint  (Figs.  16  and  17). — The 
knee-joint  is  made  up  of  the  femur,  patella,  tibia  and  fibula,  and 
is  provided  with  the  following  ligaments: 

The  ligamentum  extero-laterale  genu  is  a  strong  ligament  extending 
from  the  condylus  externus  femoris,  or  external  femoral  condyle 
to  the  outer  surface  of  the  head  of  the  fibula,  or  capitulum  fibulae. 

5 


66 


ANATOMY   OF   THE   DOMESTIC   FOWL 


From  this  head  there  passes  inward,  a  strong  ligament  to  a  point 
between  the  femur  and  fibula  (Fig.  25,  No.  D,  4). 

The    ligamentum   inter o-later ale    genu    extends    from    the    outer 
surface  of  the  internal  condyle  of  the  tibia,  or  condylus  internus 


tibiae.  It  gives  off  a  thin  ligamentous  slip  which  enters  the  joint 
and  is  attached  to  the  inner  half -moon  shaped  pad  of  fibrous 
cartilage,  or  meniscus,  which  it  draws  backward  by  the  flexion  of 
the  knee  (Fig.  16,  No.  B,  2). 


ARTHROLOGY  67 

The  ligamentum  popliteum  arises  from  the  fossa  poplitea  of  the 
distal  extremity  of  the  femur  and  extends  downward  to  the  posterior 
rim  of  the  head  of  the  tibia. 

The  anterior  ligamentum  cruciatum  genu  originates  from  the  f055a~ 
poplitea  and  extends  outward  antero-laterally  to  the  rim  of  the 
head  of  the  tibia  (Fig.  25,  No.  6). 

The  posterior  ligamentum  cruciatum  genu  is  a  short,  strong  liga- 
ment which  originates  from  the  cavity  of  the  internal  condyle 
of  the  femur,  or  condylus  internus  femoris,  and  inserts  into  the 
internal  glenoid  cavity  of  the  tibia  (Fig.  25,  No.  i)  or  cavitas  gle- 
noidalis  interna. 

The  meniscus  of  the  femoro-tibial  articulation  is  divided  into 
four  parts,  as  follows:  first,  the  internal  adhesio  cornu  antici  carti- 
laginis  lunala;  second,  the  posterior  adhesio  cornu  antici  carlilaginis 
lunate;  third,  the  external  cornu  cartilaginis  lunatce;  fourth,  the 
anterior  cornu  antici  cartilaginis  lunatce.  The  latter  originates 
between  the  condyles  and  passes  around  the  ligamentum  cruciatum 
genu  posticum  (Fig.  16,  No.  B,  7). 

The  inner  semi-lunar  fibrous  cartilage  is  well  developed  and  is 
joined  by  two  ligaments  between  the  femoral  and  the  tibial  surfaces 
(Fig.  25,  No.  i). 

The  external  semi-lunar  cartilage  lies  in  a  cavity  between  the 
external  femoral  condyle  and  the  head  of  the  fibula  (Fig.  25,  No.  2). 

The  fibrous  cartilages  are  bound  posteriorly  by  a  ligament, 
and  by  a  second  ligament  to  the  head  of  the  fibula,  or  capitulum 
fibulae.  Both  pads  of  fibrous  cartilage  are  connected  by  a  transverse 
ligament  called  the  ligamentum  transversale  commune  (Fig.  25,  No.  5). 

The  patella  is  provided  with  several  ligaments,  as  follows: 

The  anterior  patellar  ligament,  broad,  strong,  and  irregular  in 
thickness,  extends  from  the  inferior  margin  of  the  patella  to  the 
rim  of  the  second  tibial  crest  (Fig.  16,  No.  B,  3). 

Internal  ligamentum  laterale  genu.     3,  Anterior  patellar  ligament.     4,  Patella. 

5,  Distal  end  of  femur.     6,  Proximal  end  of  tibia.     7,  Location  of  meniscus  or 
pad  of  fibrocartilage. 

C.  Anterior  view  of  tibio-tarsal  articulation,  i.  Distal  end  of  tibia.  2,  Its 
articular  surface.  3,  Ligamentum  anticum.  4,  Proximal  end  of  metacarpus. 

6,  Pad  of  fibro-cartilage. 

£>.  The  dorsal  surface  of  the  coccyx.  I,  The  bilobate  oil  gland.  2,  Its  duct. 
3,  Levator  coccygis. 

E.  Inside  view  of  pelvis  and  thigh,  i,  Obturator  internus.  2,  Ambiens.  3, 
Vastus  internus.  4,  Internal  ligamentum  laterale  genu.  5,  Tibialis  anticus. 
6,  Loop  through  which  the  tibialis  anticus  passes.  7,  Adductors  of  the  thigh. 
8,  Loop  for  the  extensor  tendon. 


68 


ANATOMY   OF   THE   DOMESTIC   FOWL 


The  ligamenlum  capsulare  capituli  fibula  is  spread  out  between 
the  head  of  the  fibula,  or  capitulum  fibulae,  and  the  superficies 
glenoidalis  peronea  tibiae. 


FIG.   17. — Muscles  and  tendons  of  the  Head  and  posterior  extremity. 

A.  Section  of  neck  with  superficial  muscles  removed.  i,  Obliquo-transver- 
sales.  2,  Interspinales.  3,  Intertransversales.  4,  Interarticulares. 

jB.  Head  showing  muscles,  i,  Beak.  2,  Nostril.  3,  Tongue.  4,  Sublingual 
salivary  gland.  5,  Pterygoideus.  6,  Stylo-hyoideus.  7,  Temporal.  8,  Flexor 
capitis  inferior.  9,  Rectus  capitis  lateralis.  10,  Rectus  capitis  posticus  major. 
ii,  Trachelo-mastoideus.  12,  Eye.  13,  Mylo-hyoideus.  14,  Genio-hyoideus. 
15,  Biventer  maxilla.  16,  Digastricus.  17,  Rectus  capitis  anterior  minor. 

C.  Foot  of  hen  showing  tendons.      I,  Flexor  perforans  digitorum  profundus. 

2,  Flexor  perforatus  medius  primus  pedis.     3,  Sheath  at  joint  through  which 
tendon  passes.     4,  Flexor  perforatus  indicis  primus  pedis.     5,  Flexor  perforatus 
medius  secundus  pedis.     6,  Flexor  perforatus  annularis  primus  pedis.     7,  Flexor 
longus  hallucis. 

D.  Outside  view  of  leg  of  hen.     i,  Biceps  flexor  cruris.     2,  Semitendinosus. 

3,  Loop  through  which  biceps  flexor  cruris  passes.     4,    Tibialis   anticus.      5, 
Flexor  perforatus  indicis  secundus  pedis.     6,  Flexor  perforatus  medius  primus 
pedis.     7,    Gastrocnemius.     8,    Flexor   perforatus   annularis   primus   pedis.     9, 
Flexor  perfcratus  medius  secundus  pedis.      10,  Extensor  longus  hallucis. 

The  ligamentum  tibio-fibulare  extends  from  the  head  of  the  fibula, 
or  capitulum  fibulae,  to  the  inner  surface  of  the  external  crest, 
or  crista  externa  tibiae,  of  the  tibia  (Fig.  25,  No.  3). 


ARTHROLOGY  69 

The  ligamentum  interosseum  is  a  delicate  ligament  located  between 
the  tibia  and  fibula  (Fig.  25,  No.  4)  which  very  early  becomes 
ossified. 

Ligaments  of  the  Tibio-metatarsal  Joint  (Fig.  16). — The -tibia- 
tarsal  joint  is  made  up  of  the  tibia  and  metatarsus. 

The  ligamentum  capsulare  ossis  tibio-metatarsi  connects  the  tibia 
and  the  metatarsus  and  surrounds  the  joint  (Fig.  16,  Nos.  A,  7  and 

C,  7). 

The  ligamentum  externum,  a  long  strong  ligament,  originates  on 
the  upper  and  outer  surface  of  the  external  condyle,  or  condylus 
externus  of  the  tibia  and  is  attached  to  the  upper  rim  of  the  os 
metatarsi  (Fig.  23,  No.  15). 

The  ligamentum  anticum  is  spread  out  between  the  fossa  inter- 
condyloidea  of  the  tibia  and  the  tuberculum  ossis  metatarsi  of  the 
proximal  end  of  the  metatarsus  (Fig.  16,  No.  C,  3).  Just  posterior 
to  this  ligament,  there  is  an  interosseous  ligament,  the  ligamentum 
interosseum. 

A  semilunar  pad  of  fibrous  cartilage,  the  cartilago  semilunaris 
is  located  between  the  outer  distal  extremity  of  the  tibia  and  upper 
articular  surface  of  the  metatarsus  (Fig.  16,  No.  C,  6).  Its  concave 
portion  is  directed  anteriorly  and  receives  an  insertion  from  the 
ligamentum  externum,  or  external  ligament. 

The  tendon  Achillis  (Fig.  16,  No.  A,  i)  may  become  ossified. 

Ligaments  of  the  Toes  (Fig.  16). — In  addition  to  the  capsular 
ligaments,  which  all  true  joints  have,  we  find  the  following  in  con- 
nection with  the  toes: 

The  ligamentum  superius  and  the  ligamentum  inferius  connect 
the  second  toe  with  the  great  toe,  or  hallux. 

The  ligamentum  laterale  externum  and  the  ligamentum  laterale 
internum  unite  the  bases  of  the  second,  third  and  fourth  toes  to 
the  lateral  faces  of  the  trochleas  of  the  inferior  extremity  of  the 
metatarsus. 

The  bases  of  the  toes  are  held  together  by  the  ligamenta  transversa. 
All  the  rest  of  the  toes  are  held  together  by  the  ligamenta  capsularia 
digitorum  pedis  and  by  two  lateral  ligaments,  namely:  the  ligamentum 
laterale  externum  and  the  ligamentum  laterale  internum. 


MYOLOGY 

Kinds  and  Structure  of  Muscles. — Muscles  are  highly  specialized 
structures  which  have  the  property  of  contractility  when  stimulated, 
and  thus  produce  motion.  Muscular  tissue  is  sometimes  called 
flesh.  Two  kinds  of  muscles  are  recognized;  muscles  of  locomotion 
and  visceral  muscles. 

The  muscles  of  locomotion  may  be  in  masses  of  different  shape 
attached  to  the  skin,  the  dermal,  or  to  the  skin  and  skeletal  structure, 
the  dermo-osseous ,  or  from  one  bone  to  another,  the  skeletal.  The 
visceral  muscles  form  sheets  and  make  up  a  portion  of  the  wall  of 
many  of  the  hollow  organs,  such  as  the  intestines,  the  stomach, 
the  gizzard,  the  esophagus,  and  the  blood-vessels.  A  special  type 
of  muscle  forms  the  heart. 

When  classified  with  reference  to  structure,  muscular  tissue 
is  divided  into  three  types,  as  follows:  voluntary-striated,  in- 
voluntary, and  involuntary-striated.  The  microscopic  examination 
of  each  of  these  types  of  muscle  shows  it  to  be  made  up  of  fibers, 
these  fibers  to  be  made  up  of  muscle  cells,  the  muscle  cell  to  be  in- 
closed in  a  delicate  tubular  sheath,  or  membrane,  called  the  sarco- 
lemma.  This  membrane,  tough  and  elastic,  isolates  each  fiber. 
The  bundles  of  fibers,  called  fasciculi,  are  surrounded  by  a  fibrous 
sheath,  which  is  called  the  perimysium  internum;  and  the  entire 
muscle  has  likewise  an  investing  sheath  of  connective  tissue,  called 
the  perimysium  externum.  The  muscular  cells  show  a  longitudinal 
striation  marking  the  fibrillae,  and  they  also  show  a  cross  striation. 
Nuclei  are  found  just  beneath  the  covering,  or  sarcolemma,  in  the 
striated  muscle  cell  (Fig.  77,  No.  2).  In  the  involuntary  and  in  the 
involuntary-striated  muscle  cell,  the  nuclei  are  centrally  located. 

The  voluntary-striated  muscles^ consist  of  cylindrical  fibers  and  with 
a  few  exceptions,  are  under  the  control  of  the  will.  A  muscle  of 
this  type,  the  regular  skeletal  form,  usually  has  at  each  extremity  a 
fibrous  structure,  called  a  tendon,  by  means  of  which  it  is  attached 
to  the  bones.  The  intermediate  fleshy  portion  of  the  muscle,  in 
case  of  considerable  bulk,  is  called  the  belly  of  the  muscle. 

The  involuntary,  non-striated,  or  smooth  muscle,  cells  are  spindle- 
shaped,  long,  and  pale  in  color  (Fig.  77,  No.  i).  The  cells  lie  end  to 
end  forming  fibers.  These  fibers  do  not  terminate  in  tendons,  but 

70 


MYOLOGY  71 

are  arranged  in  sheets  and  aid  in  forming  the  walls  of  the  digestive 
tract,  to  which  they  give  the  power  of  contraction  and  expansion. 

Involuntary-striated,  or  heart  muscle  (Fig.  77,  No.  4),  occupies 
an  intermediate  position  between  the  two  muscles  just  described. 
It  is  composed  of  cells  which  branch,  are  somewhat  rectangular. 
They  possess  both  longitudinal  and  transverse  striation.  Among 
the  fibers  is  found  a  small  amount  of  connective  tissue,  as  in  the 
former  types  of  muscle,  which  gives  support  to  the  blood-vessels 
and  nerves. 

Fascia. — The  term  fascia  is  applied  to  membranous  expansions, 
differing  materially  in  strength,  texture,  and  relations.  Fascia  is 
composed  of  loosely  arranged  white  fibrous  connective  tissue.  At 
least  two  layers  may  usually  be  distinguished,  the  superficial  fascia 
and  the  deep  fascia. 

Below  the  skin  is  the  superficial  fascia,  which  forms  a  continuous 
covering  over  the  whole  body  and  serves  to  attach  the  skin  to  the 
underlying  structure. 

The  deep  fascia  more  densely  constructed,  may  be  attached  to 
the  skeleton,  ligaments,  and  tendons. 

When  the  fascia  spreads  out,  becomes  denser,  and  acts  as  a  con- 
tinuation of  a  mucle,  it  is  called  an  aponeurosis. 

The  Muscular  Nomenclature. — In  the  fowl  there  are  162  muscles, 
single  or  in  pairs.  These  muscles  are  named  from  their  location, 
as  the  lingualis;  others  from  their  attachments,  as  the  dermo-tem- 
poralis;  some  from  their  form,  as  the  rhomboideus;  others  from  their 
use,  as  the  flexor  or  extensor;  and  still  others  from  their  direction, 
as  the  transversus. 

THE  DERMAL  MUSCLES 

Birds  are  provided  with  a  system  of  delicate  muscles  divided  into 
numerous  fasciculi,  which  harmoniously  act  upon  the  feather  quills 
and  collectively  agitate  the  plumage.  These  are  the  dermal  muscles. 
This  group  is  divided  into  two  subgroups :  the  true  dermal  muscles, 
that  is,  those  that  have  their  origin  and  insertion  to  the  under  sur- 
face of  the  skin;  and  the  dermo-osseous,  those  that  originate  on  the 
surface  of  some  bone  and  insert  to  the  inner  surface  of  the  skin. 

TRUE  DERMAL  MUSCLES 

Dermo-frontalis  Dermo-dorsalis 

Dermo-tensor  patagii  Dermo-humeralis 

Dermo-pectoralis 


72  ANATOMY   OF   THE   DOMESTIC   FOWL 

Dermo-frontalis.1  Location. — This  muscle  is  somewhat  rudimen- 
tary and  may  be  entirely  absent.  It  is  located  in  the  frontal  region 
and  is  about  2  or  3  centimeters  long  and  not  so  wide. 

Origin  and  Insertion. — Closely  attached  to  the  skin. 

Shape. — Flat  and  rather  rectangular. 

Relations. — Superiorly  with  the  skin  and  inferiorly  with  the  frontal 
bones. 

Action. — By  contraction  the  feathers  on  the  top  of  the  head  lie 
flat.  Those  above  the  eyes  are  elevated. 

Dermo-dorsalis.  Location. — In  the  median  line  of  the  neck  and 
back. 

Origin  and  Insertion. — Adhering  closely  to  the  skin,  it  generally 
becomes  lost  at  the  occiput;  it  is  most  highly  developed  in  the 
mid-cervical  region,  and  it  gradually  disappears  over  the  caudal 
region. 

Shape. — Delicate  and  ribbon-shaped. 

Relations. — Superiorly  it  is  attached  to  the  skin.  Fat  sometimes 
surrounds  the  muscle. 

Action. — By  contraction  it  raises  the  feathers  along  the  superior 
part  of  the  neck  and  dorsal  region. 

Dermo-tensor  Patagii.  Location. — Between  the  root  of  the  neck 
and  top  of  the  shoulder. 

Origin  and  Insertion. — Attached  to  the  skin  in  the  region  of  the 
anterior  part  of  the  root  of  the  neck,  some  fibers  passing  obliquely 
upward  and  blend  with  fibers  of  the  dermo-temporalis.  It  blends, 
by  a  slender  tendon,  with  that  of  the  tensor  patagii  longus. 

Shape. — A  bundle  of  muscular  fibers  later  becomes  thin,  delicate, 
and  triangular  in  shape. 

Relations. — Externally  to  the  skin. 

Action. — Auxiliary  to  the  tensor  patagii  longus.  A  tensor  of 
this  region. 

The  patagii  are  associated  with  the  wing  fold  of  skin  which  fills 
the  angle  between  the  arm  and  forearm.  This  fold  contains  elastic 
tissue  and  muscle. 

Dermo-humeralis.    Location. — Lateral  thoracic  region. 

Origin  and  Insertion. — Fan-like  delicate  fibers  from  the  skin  in 
the  abdominal  integument,  contracting  into  a  long  narrow  fasci- 
culus of  fibers,  again  spreading  out  in  fan-shape  to  be  inserted  to  the 
tendon  of  the  pectoralis  major,  just  below  its  insertion. 

classification  of  Shufeldt  is  used. 


MYOLOGY  73 

Shape. — Triangular,  fan-shape. 

Relations. — Superiorly  with  the  skin. 

Action. — Controls  the  skin  in  this  region.  The  anterior  end  being 
fixed,  the  muscles  are  raised;  and  the  posterior  end  acting  as  the 
fixed  point,  the  feathers  are  caused  to  lie  close  to  the  body. 

Dermo-pectoralis.  Location. — On  each  side  of  the  chest,  lying 
in  a  longitudinal  manner. 

Origin  and  Insertion. — Attached  to  the  skin  on  either  side  of  the 
thorax  corresponding  to  the  dermo-dorsalis.  Anteriorly  it  disap- 
pears over  the  region  of  the  origin  of  the  cleido-trachealis,  and  pos- 
teriorly just  behind  the  tips  of  the  postpubic  parts  of  the  pelvis. 

Shape. — Thin,  delicate. 

Relations. — Superiorly  with  the  skin. 

Action. — The  anterior  part  acting  as  the  fixed  point,  the  feathers 
of  the  chest  are  raised;  and  the  posterior  end  acting  as  the  fixed 
point,  the  feathers  are  made  to  lie  flat. 

THE  DERMO-OSSEOUS  MUSCLES 

Dermo-temporalis  Platysma  myoides 

Dermo-cleido  dorsalis  Cleido-trachealis 

Dermo-spinalis  Dermo-iliacus 

Dermo-ulnaris 


Dermo-temporalis  (Fig.  18,  No.  i).  Location. — From  the  tempo- 
ral region  down  the  side  of  the  neck  to  the  anterior  part  of  the 
thoracic  region. 

Origin. — By  a  broad  tendinous  attachment  from  a  small  depres- 
sion above  and  anterior  to  the  temporal  fossa.  From  here  the 
fibers  pass  upward  and  backward  and  then  downward. 

Insertion. — A  few  fibers  blend  with  those  of  the  cleido-trachealis. 
The  fibers  are  then  lost  upon  the  skin  in  front  and  opposite  the 
shoulder-joint.  Some  of  the  fibers  blend  with  those  of  the  dermo- 
tensor  patagii. 

Shape. — Long,  flat,  and  ribbon-shaped.  The  lower  portion  con- 
sists of  delicate  fibers. 

Relations.' — Superior  to  the  temporal  muscle  and  sphenotic 
process.  Superior  to  the  cleido-trachealis  and  inferiorly  to  the 
shoulder-joint.  The  superior  portion  touches  the  skin  throughout 
its  entire  length. 


74 


ANATOMY   OF   THE  DOMESTIC  FOWL 


Action. — A  tensor  of  the  lateral  cervical  integument.  It  is  an 
auxiliary  to  the  tensor  patagii. 

Platysma  Myoides.    Location. — The  inferior  portion  of  the  throat. 

Origin. — From  the  lower  margin  of  the  rami  of  the  jaw.  Just 
inferior  to  the  attachment  of  the  masseter. 


FIG.  18. — Muscles  of  the  upper  neck  region,  i,  Dermo-temporalis.  2,  Cornu 
of  the  os  hyoideum.  3,  Carotid  artery.  4,  Jugular  vein.  5,  Pneumogastric 
nerve.  6,  Esophagus.  7,  Trachea. 

Insertion. — From  the  point  of  origin  it  spreads  out  into  a  thin 
fan-like  layer  and  meets  its  fellow  in  the  median  raphe.  It  is 
attached  to  the  skin  in  this  region. 

Shape. — A  very  thin  fan-shaped  muscle. 

Relations. — Closely  adherent  to  the  skin. 

Action. — Assists  in  supporting  the  lingual  apparatus  and  superior 
Jarynx.  Compresses  and  elevates  the  part. 


MYOLOGY  75 

Dermo-cleido  Dorsalis.    Location. — Anterior  shoulder  region. 

Origin. — From  the  upper  mesial  part  of  the  clavicular  bone. 

Insertion. — Three  fasciculi  forming  a  fan-like  arrangement  at- 
tached to  the  skin  in  the  shoulder-joint  and  scapular  region.  The 
extremities  of  the  fasciculi  may  meet  in  the  median  line  of  the 
dorsal  region  and  merge  with  the  dermo-dorsalis. 

Shape. — Three  fasciculi  forming  a  fan-shaped  radiation. 

Relations. — Superiorly  with  the  skin.  Inf  eriorly  with  the  shoulder- 
joint. 

Action. — Contracting  with  the  origin  as  the  fixed  point,  they 
brace  the  skin  over  the  forepart  of  the  back.  With  the  integumental 
attachment  as  the  fixed  point,  they  aid  in  the  act  of  respiration. 

Cleido-trachealis.  Location. — Extending  from  the  shoulder  to 
the  superior  laryngeal  region. 

Origin. — From  a  small  area  on  the  antero-inner  part  of  the  middle 
of  the  arm  of  the  furcula. 

Insertion. — The  fibers  pass  upward  and  become  flattened  and 
attached  to  the  skin  and  dermo-temporalis  muscle.  They  touch 
each  other  on  the  anterior  border  of  the  superior  larynx,  the  trachea, 
and  the  skin  over  these  parts. 

Shape. — A  slender  bundle  of  muscles. 

Relations. — Superiorly  the  skin,  and  internally  the  larynx  and 
the  trachea. 

Action.- — Controls  the  skin  region  of  this  part  of  the  neck. 

Dermo-spinalis.    Location. — In  the  region  of  the  shoulder. 

Jrigin. — In  an  attenuated  fascia  from  the  crest  of  the  neural 
spines  of  the  first,  the  second,  and  the  third  dorsal  vertebrae. 

Insertion.- — To  the  skin  in  a  broad  pale  stratum,  over  the  scapular 
region. 

Shape. — Thin,  pale,  and  very  delicate. 

Relations.— Superiorly  with  the  skin,  and  inferiorly  with  the 
shoulder. 

Action. — Controls  the  skin  of  the  region. 

Dermo-iliacus.  Location. — Along  the  back  on  either  side  of  the 
spine. 

Origin. — From  the  inner  angle  of  the  marginal  portion  of  the 
antero-dorsal  border  of  the  ilium. 

Insertion. — Passing  forward  as  a  delicate  band  it  spreads  out  and 
becomes  lost  in  the  skin  of  the  shoulder  region. 

Shape. — Thin,  delicate,  and  ribbon-shaped. 


76  ANATOMY  OF  THE  DOMESTIC  FOWL 

Relations. — Superiorly  with  the  skin. 

Action. — If  the  posterior  end  is  fixed,  it  will  cause  the  feathers 
to  lie  close  to  the  skin.  Its  action  would  then  be  opposite  to  the 
dermo-dorsalis. 

Dermo-ulnaris.  Location. — Outer  surface  of  the  anterior  upper 
costal  and  the  posterior  humeral  region. 

Origin. — By  a  thin  fascia  from  the  outer  part  of  the  third  and  the 
fourth  true  ribs  at  the  base  of  their  epineural  appendages.  Also 
from  the  fascia  between  them. 

Insertion. — The  fibers  pass  forward  and  upward  as  a  thick 
muscular  bundle  and  is  loosely  attached  to  the  skin  at  a  point  just 
back  of  the  humerus.  The  tendon  later  becomes  spread  out  and 
attached  to  the  fascia  as  far  as  the  elbow-joint.  It  covers  the 
olecranon  of  the  ulna. 

Shape. — At  first  rather  thick,  fascicular-like;  later  becomes 
tendinous;  and  at  its  attachment  it  becomes  spread  out  over  the 
olecranon. 

Relation. — Inferiorly  with  the  ribs  and  humerus,  and  externally 
with  the  skin. 

Action. — A  depressor  of  the  humeral  region. 

THE  SKELETAL  MUSCLES 
THE  MUSCLES  OF  THE  HEAD 

Temporal  Masseter 

Biventer  maxillae  Entotympanicus 

Pterygoideus  internus  Pterygoideus  externus 

Digastricus 


Temporal  (Fig.  19,  No.  4).  Location. — Occupies  the  temporal 
fossa. 

Origin.' — From  the  mesian  line  of  the  sphenotic  process,  and  the 
adjacent  wall  of  the  orbit. 

Insertion. — The  fibers  passing  downward  and  forward  blend  with 
the  fibers  of  the  masseter.  Inferiorly  it  inserts  by  a  tendon  to  the 
coranoid  process  upon  the  superior  ramal  margin  of  the  mandible. 

Shape. — Fan-shaped  with  broad  portion  uppermost. 

Relations. — It  occupies  the  temporal  fossa.  It  is  related  superiorly 
with  the  dermo-temporalis  and  skin.  Inferiorly,  with  the  biventer 
maxillae  and  the  masseter. 


MYOLOGY  77 

Action. — It  aids  in  closing  the  jaw. 

Masseter  (Fig.  19,  No.  i).  Location. — Occupies  the  supero-lat- 
eral  portion  of  the  surface  of  the  lower  jaw. 

Origin. — In  two  portions:  the  first,  by  a  broad  and  thin  tendon 
from  the  entire  length  of  the  bony  ridge  above  the  external  auditory 
meatus,  from  the  squamosal  process,  and  from  the  outer  portion  of 
the  quadrate  bone;  the  second,  from  the  side  and  under  border  of 
the  zygoma. 

Insertion. — The  first  portion:  The  fibers  pass  downward  and  for- 
ward beneath  the  zygoma;  a  few  of  the  fibers  blend  with  those  of  the 
temporal;  one  tendon  inserts  to  a  small  tubercle  on  the  upper  border 
of  the  jaw  behind  the  coronoid  process,  and  by  fleshy  insertion 
to  the  outer  side  of  the  ramus  of  the  lower  jaw,  quite  as  far  forward 
as  the  horny  portion  of  the  beak.  The  second  portion:  by  a  small 
tendon  to  the  mandible  on  its  upper  border  immediately  in  front  of 
the  articular  portion. 

Shape. — Flat,  and  elongate.     Somewhat  fleshy. 

Relations. — Superiorly  with  the  temporal,  and  inferiorly  with  the 
biventer  maxillae  and  stylo-hyoideus.  Externally  with  the  skin, 
and  internally  with  the  jaw  bone. 

Action. — Aids  in  closing  the  jaw. 

Biventer  Maxillae  (Fig.  19,  No.  3).  Location. — Covers  the  outer 
posterior  portion  of  the  mandible. 

Origin. — It  arises  in  two  portions:  The  first,  from  a  ridge  bounding 
the  posterior  part  of  the  auditory  canal;  the  second,  from  a  depres- 
sion of  the  mesial  side.  These  two  parts  blend  and  extend  downward 
and  forward. 

Insertion. — To  the  posterior  part  of  the  articular  end  of  the 
mandible. 

Shape. — A  curved  fleshy  mass. 

Relations. — Superiorly  with  the  temporal  and  stylo-hyoideus. 
Posteriorly  with  the  digastricus  and  genio-hyoideus.  Internally 
with  the  jaw  bone,  and  externally  with  the  skin. 

Action. — It  aids  in  opening  the  jaw. 

Entotympanic.    Location. — Posterior  to  the  pterygoid. 

Origin. — From  the  side  of  the  basi-sphenoid  and  from  the  base  of 
the  rostrum  immediately  beyond  it. 

Insertion. — The  fibers  pass  downward  and  forward,  and  insert  by  a 
double  tendinous  slip.  One  slip  inserts  to  a  spine-like  process  on 


78  ANATOMY   OF   THE  DOMESTIC  FOWL 

the  upper  side  of  the  pterygoid,  and  the  other  to  the  quadrato-ptery- 
goidean  articulation. 

Shape. — Spindle-shaped. 

Relations. — Anteriorly  with  the  pterygoid.  Internally  and  pos- 
teriorly with  the  basi-sphenoid.  Externally  with  the  pterygoideus 
internus. 

Action. — Aids  in  raising  the  upper  mandible  by  pulling  forward 
the  quadra tus  and  pterygoidean  against  the  palatines. 

Pterygoideus  Internus  (Fig.  17,  No.  B,  5).  (Synonym. — Ptery- 
goideus median's.1) 

Location. — A  muscular  mass  at  the  roof  of  the  mouth. 

Origin. — From  the  major  part  of  the  surface  of  the  palatine  bone 
and  the  distal  head  and  shaft  of  the  pterygoid  and  the  sphenoidal 
projection. 

Insertion. — By  a  tendon  to  the  antero-internal  part  of  the  articular 
part  of  the  mandible. 

Shape.- — Fusiform  with  a  thick  fleshy  belly. 

Relations. — Superiorly  with  the  palatine,  the  pterygoid,  and  the 
sphenoid  bones.  Inferiorly  with  the  skin. 

Action. — It  aids  in  closing  the  jaw. 

Pterygoideus  Externus.     (Synonym. — Pterygoideus  lateralis.) 

Location. — Supero-external  to  the  pterygoideus  internus. 

Origin. — From  the  outer  part  of  the  extremity  of  the  orbital  proc- 
ess of  the  quadrate. 

Insertion. — The  fibers  pass  downward,  outward  and  forward  and 
are  inserted  to  the  inner  part  of  the  mandibular  ramus. 

Shape. — A  small  round  bundle. 

Relations. — Inferiorly  with  the  pterygoideus  internus.  Externally 
with  the  inferior  maxilla. 

Action. — Aids  in  closing  the  jaw. 

Digastricus  (Fig.  17,  No.  B,  16).  Location. — Extends  from  the 
basi-temporal  to  the  side  of  the  neck. 

Origin. — From  the  external  lateral  angle  of  the  basi-temporal. 

Insertion. — Opposite  the  angle  of  the  jaw  the  fibers  spread  out  in 
fan-like  arrangement.  The  muscle  meets  its  fellow  of  the  opposite 
side;  extends  longitudinally  over  the  superior  larynx,  for  some 
distance  down  the  neck. 

Shape. — Thin  and  ribbon-shaped. 

Relations. — Externally  to  the  platysma  myoides.     The  anterior 

1  According  to  international  veterinary  nomenclature- 


MYOLOGY  79 

fasciculi  blend  with  those  of  the  mylo-hyoideus;  internally  with  the 
larynx  at  the  upper  part. 

Action. — To  raise  the  trachea  and  hyoid  apparatus  against  the 
pharynx. 

THE  MUSCLES  OF  THE  TONGUE 

Mylo-hyoideus  Stylo-hyoideus 

Genio-hyoideus  Cerato-hyoideus 

Sterno-hyoideus  Depressor-glossus 

Cerato-glossus  Hyoideus  transversus 

Mylo-hyoideus.  Location. — The  forepart  of  the  inter-ramal 
space.  * 

Origin. — From  the  inner  side  of  the  lower  jaw  at  a  point  just 
above  the  lower  border  and  the  inturned  edge  of  the  horny  sheath  of 
the  beak. 

Insertion. — By  aponeurosis  to  the  under  side  of  the  hyoid,  on  the 
median  line  between  the  first  and  the  second  basi-branchial. 

Shape.- — Thin,  flat,  and  delicate. 

Relations. — Inferiorly  with  the  skin.  Thin  and  rather  broad,  it 
meets  its  fellow  of  the  opposite  side.  Laterally  with  the  rami 
of  the  jaw.  Superiorly  with  the  hyoid  apparatus. 

Action.' — Lifts  the  tongue  upward  against  the  roof  of  the  mouth. 

Stylo-hyoideus  (Fig.  17,  No.  B,  6).  Location. — Supero-posterior 
to  the  hyoid  apparatus. 

Origin. — From  the  outer  portion  of  the  articular  enlargement  of 
the  lower  jaw. 

Insertion. — By  a  tendon  to  the  basi-branchial  of  the  thyro-hyal. 

Shape. — A  long  transversely  flattened  fasciculus. 

Relations. — Supero-posterior  part  of  the  hyoid  apparatus  along 
side  the  genio-hyoideus  and  the  cerato-hyoideus. 

Action. — Singly,  pulls  the  tongue  to  one  side;  acting  with  its 
fellow,  pulls  the  tongue  upward. 

Genio-hyoideus  (Fig.  9,  No.  7).  Location. — Supero-posterior  to 
the  hyoid  apparatus. 

Origin. — From  the  anterior  portion  of  the  inner  side  of  the  lower 
jaw. 

Insertion. — To  the  middle  of  the  outer  side  of  the  basi-branchial 
of  the  corner  of  the  os  hyoides  which  cornu  it  completely  envelops. 

Shape.- — A  long,  rather  thick  fasciculus. 

Relations. — With  the  stylo-hyoideus  and  cerato-hyoideus. 


80  ANATOMY  OF  THE  DOMESTIC  FOWL 

Action. — Protrudes  the  tongue  from  the  mouth. 

Cerato-hyoideus  (Fig.  9,  No.  8).     (Synonym.— Kerato  hyoideus.) 

Location. — Inferior  to  the  hyoid  apparatus. 

Origin. — By  a  delicate  tendinous  slip  from  the  under  side  of  the 
shaft  of  the  basi-hyal  element  of  the  hyoid-apparatus. 

Insertion. — To  a  small  elevation  on  the  under  side  of  the  anterior 
end  of  the  glosso-hyal. 

Shape. — A  small  round  muscular  fasciculus  becoming  tendinous  in 
its  anterior  half. 

Relations. — Superiorly  with  the  hyoid  apparatus. 

Action. — Singly,  pulls  the  tongue  to  one  side;  acting  with  its 
fellow,  depresses  the  tongue.  i  . 

Sterno-hyoideus.    Location. — Inferior  to  the  hyoid  apparatus. 

Origin. — From  the  outer  anterior  surface  of  the  thyroid  bone  of 
the  superior  larynx. 

Insertion. — To  the  anterior  part  of  the  basi-hyal. 

Shape. — At  first  broad  and  rather  fleshy,  becomes  contracted  and 
somewhat  tendinous. 

Relations. — Inferior  to  the  hyoid  apparatus  and  superior  larynx. 

Action. — When  the  larynx  is  fixed,  acting  alone  deflects  the  tongue 
laterally;  acting  with  its  fellow,  depresses  the  tongue.  If  the  base 
of  the  tongue  is  fixed  the  two  pull  the  larynx  forward.  Hence 
muscles  of  deglutition. 

Depressor-glossus.    Location. — Superior  to  the  basi-hyal. 

Origin. — From  the  under  portion  of  the  basi-hyal. 

Insertion. — To  under  part  of  the  glosso-hyal. 

Shape. — Small,  short. 

Relations. — Superiorly  with  the  basi-hyal  and  glosso-hyal  bones. 

Action. — Depresses  the  tip  of  the  tongue  and  elevates  the  base. 

Cerato-glossus.  Location. — On  the  upper  portion  of  the  cornu 
of  the  hyoid. 

Origin. — One-half  of  the  surface  of  the  first  basi-branchial. 

Insertion. — To  the  upper  side  of  the  shaft  of  the  cerato-branchial 
element  of  the  hyoid  apparatus. 

Shape. — A  small  muscular  fasciculus. 

Relations. — Supero-laterally  to  the  cerato-branchial  element. 

Action. — Elevates  the  cornua  of  the  hyoid  arches  and  presses  them 
against  the  skull. 

Hyoideus  Transversus  (Fig.  9,  No.  9  and  10).  Location. — 
Envelops  the  spur  process  of  the  euro-hyal. 


MYOLOGY  8 I 

Origin  and  Insertion. — It  extends  from  the  inner  side  of  one  cornu 
to  the  spur  process. 

Shape.— Thin,  flat. 

Relations. — Posterior  to  the  euro-hyal,  which  it  envelops, 
between  the  cornua  of  the  os  hyoides. 

Action. — Approximates  the  cornua  of  the  os  hyoides. 

THE  CERVICAL  MUSCLES 

Complexus  Rectus  capitis  anticus  minor 

Flexor  capitis  inferior  Rectus  capitis  posticus  major 

Biventer  cervicis  Longus  colli  posticus 

Obliquus  colli  Longus  colli  anterior 

Rectus  capitis  lateralis  Trachelo-mastoideus 

Interspinales  Interarticulares 

Obliquo-transversales  Intertransversales] 
Scalenus  medius 


Complexus  (Fig.  19,  No.  5).  Location. — Supero-lateral  portion 
of  the  neck. 

Origin. — By  three  tendinous  slips  from  the  antero-lateral  portion 
of  the  transverse  process  of  the  fourth,  the  fifth,  and  the  sixth 
cervical  vertebrae. 

Insertion. — The  muscular  fibers  pass  around  the  neck  and  meet 
their  fellows  in  the  median  line  in  a  fascia  formation.  The  thin 
tendinous  sheet  inserts  into  the  occiput  just  above  the  occipital 
ridge. 

Shape. — From  point  of  origin  this  muscle  expands  into  a  broad 
sheet. 

Relations. — It  overlies  the  muscles  of  the  occipital  region. 

Action. — It  extends  the  head. 

Rectus  Capitis  Anticus  Minor  (Fig.  19,  No.  8).  (Synonym. — 
Rectus  capitis  ventralis  minor.) 

Location. — Infero-lateral  portion  of  the  neck. 

Origin. — From  the  apices  of  the  hyapophyses  of  the  second, 
the  third,  and  the  fourth  cervical  vertebae. 

Insertion. — To  the  occiput  just  below  the  complexus. 

Shape. — A  long  and  rather  thick  fasciculus. 

Relations. — Externally  with  the  skin.  The  tendinous  slips  of  origin 
pass  between  the  flexor  capitis  inferior  and  longus  colli  anterior. 


82  ANATOMY   OF  THE  DOMESTIC  FOWL 

4 

Action. — Extends  the  head. 

Flexor  Capitis  Inferior  (Fig.  19,  No.  7).  Location. — Antero- 
inferior  part  of  the  neck. 

Origin. — From  the  apices  of  the  hyapophyses  of  the  second,  the 
third,  and  the  fourth  cervical  vertebrae. 

Insertion. — To  the  triangular  area  on  the  basi-temporal  of  the 
base  of  the  cranium. 

Shape. — At  first  tendinous,  becomes  somewhat  fleshy  as  it  passes 
forward. 


FIG.  19. — Muscles  of  the  head  and  neck,  i,  Masseter  muscle.  2,  Infra- 
orbital  sinus.  3,  Biventer  maxilla.  4,  Temporalis.  5,  Complexus.  6,  Rectus 
capitis  posticus  major.  7,  Flexor  capitis  inferior.  8,  Rectus  capitis  anticus 
minor.  9,  Biventer  cervicis.  10,  Longus  colli  posticus.  II,  Obliquus  colli.  12, 
Intertransversales.  13,  Longus  colli  anterior.  14,  Lateral  temporo-maxillary 
ligament.  15,  Lateral  ligament  of  the  jaw.  16,  Trachelo-mastoideus.  17, 
Rectus  capitis  lateralis.  18,  Scalenus  medius.  19,  Rhomboideus.  20,  Tra- 
pezius.  21,  Location  of  scapula.  22,  Supraspinatus.  23,  Teres  et  Infraspinatus. 

Relations. — Antero-inferior  portion  of  the  neck  close  to  the  rectus 
capitis  anticus  minor. 

Action. — Flexes  the  head  upon  the  neck. 

Rectus  Capitis  Posticus  Major  (Fig.  19,  No.  6).  (Synonym.— 
Rectus  capitis  dorsalis  major.) 

Location. — Supero-lateral  area  on  the  anterior  portion  of  the 
neck. 

Origin. — From  the  median  anterior  aspect  of  the  second  cervical 
vertebra,  and  the  supero-anterior  border  of  the  neural  canal. 


MYOLOGY  83 

Insertion. — To  the  crescent-shaped  area  at  the  back  of  the  skull. 

Shape.— Short,  thick,  fleshy  bundle. 

Relations. — Superiorly  with  the  complexus;  inferiorly  with  the 
trachelo-mastoideus  and  the  vertebrae. 

Action. — Singly,  pulls  the  head  to  one  side;  acting  with  its  fellow, 
extends  the  head. 

Biventer  Cervicis  (Fig.  19,  No.  9).  Location. — Occupies  the  su- 
perior part  of  the  neck. 

Origin. — From  the  side  of  the  neural  spine  of  the  first  dorsal 
vertebra,  and  from  the  adjacent  tendon  of  the  longus  colli  posticus. 

Insertion. — To  the  occiput. 

Shape. — Tendinous  in  the  middle  with  a  more  or  less  spindle- 
shaped  belly  at  each  end. 

Relations. — Superior  to  the  longus  colli  posticus.  It  lies  next  to 
the  skin. 

Action. — Extends  the  head  on  the  neck  and  elevates  the  neck. 

Longus  Colli  Posticus  (Fig.  19,  No.  10).  (Synonym. — Longus 
colli  dorsalis.) 

Location. — Occupies  the  superior  part  of  the  neck. 

Origin. — From  the  marginal  edges  of  the  summits  of  the  neural 
spines  of  the  first  two  dorsal  vertebras. 

Insertion. — To  the  transverse  process  of  the  axis,  and  superior 
part  of  the  cervical  vertebrae. 

Shape. — A  long,  somewhat  narrow,  flattened  muscle,  the  inferior 
portion  of  which  is  divided  into  five  or  six  fasciculi. 

Relations.- — Superiorly  with  the  biventer  cervicis  and  inferiorly 
with  the  vertebrae. 

Action. — Raises  the  neck  upward. 

Obliquus  Colli  (Fig.  19,  No.  n).  Location. — On  the  lateral  side 
of  the  neck. 

Origin  and  Insertion. — The  first  of  the  seven  fasciculi  originates 
from  the  diapophysis  of  the  eleventh  cervical  vertebra,  winds  ob- 
liquely over  the  tenth,  and  is  inserted  into  the  posterior  margin 
of  the  postzygapophysis  of  the  ninth  vertebra.  In  its  passage  it 
receives  the  slip  from  the  longus  colli  posticus.  The  next  fasciculus 
originates  from  the  transverse  process  of  the  tenth  cervical  vertebra, 
winds  obliquely  over  the  ninth  vertebra,  and  is  inserted  to  the  post- 
zygapophysis of  the  eighth  vertebra.  In  its  passage  it  also  receives 
a  fasciculus  from  the  longus  colli  posticus.  The  next  three  fas- 
ciculi originate  in  a  similar  manner  being  attached  to  similar  post- 


84  ANATOMY   OF   THE   DOMESTIC   FOWL 

zygapophyses  and  have  slips  extending  forward  which  slips  are  in- 
serted to  the  neural  spines  of  the  alternate  vertebrae.  The  sixth 
fasciculus  originates  from  the  transverse  process  of  the  sixth  ver- 
tebra, passing  obliquely  up  the  neck  is  inserted  to  the  extremity  of 
the  diapophysis  of  the  fourth  vertebra,  the  outer  extremity  of  the 
transverse  process  of  the  third  vertebra.  The  seventh,  or  anterior, 
fasciculus  originates  from  the  transverse  process  of  the  fifth  vertebra, 
and  is  inserted  to  the  extremity  of  the  diapophysis  of  the  third 
vertebra. 

Shape. — Short,  thick  fasciculi. 

Relations. — Laterally  with  the  vertebras.  Inferiorly  with  the 
intertransversales.  Superiorly  with  the  longus  colli  posticus,  and 
externally  with  the  skin. 

Action. — Flexes  one  vertebra  on  the  other  laterally. 

Longus  Colli  Anterior  (Fig.  19,  No.  13).  (Synonym. — Longus 
colli  ventralis.) 

Location. — Occupies  the  anterior  portion  of  the  neck. 

Origin  and  Insertion. — This  muscle  is  divided  into  a  vertical 
portion,  and  a  superior  and  an  inferior  oblique  portion.  The  ver- 
tical portion  originates  from  the  hypophyses  of  the  tenth  to  the  fif- 
teenth vertebra  and  is  inserted  by  a  tendon  to  the  tubercle  on  the 
inferior  portion  of  the  atlas.  Small,  slender  tendons  are  given  off 
and  insert  to  the  apices  of  the  parapophyses  of  the  fourth  to  the 
tenth  cervical  vertebrae.  There  is  more  or  less  attachment  to 
the  bodies  of  the  cervical  vertebrae  mentioned.  The  superior 
oblique  portion  originates  from  the  diapophyses  of  the  third,  the 
fourth,  the  fifth  cervical  vertebrae  and  becoming  tendinous  is  in- 
serted to  the  tubercle  on  the  inferior  portion  of  the  body  of  the  atlas. 
The  inferior  oblique  portion  originates  from  the  transverse  processes 
of  the  fourth,  the  fifth,  and  the  sixth  cervical  vertebrae.  It  is 
inserted  by  a  slender  tendon  to  the  apex  of  the  parapophysis  of 
the  third  cervical  vertebra. 

Shape. — A  long  fleshy  muscle  extending  the  entire  length  of  the  neck. 

Relations.  —Inferiorly  with  the  skin  and  superiorly  with  the  cer- 
vical vertebrae. 

Action. — Pulls  the  neck  downward. 

Rectus  Capitis  Lateralis  (Fig.  19,  No.  17).  Location.— -The 
infero-lateral  anterior  portion  of  the  neck. 

Origin. — Originates  tendinous  from  the  diapophysis  of  the  third, 
the  fourth,  and  the  fifth  cervical  vertebrae. 


MYOLOGY  85 

Insertion. — Passes  obliquely  upward  in  front  of  the  spinal  column 
to  the  inner  tubercle  on  the  basal  ridge  of  the  basi-temporal  bone, 
by  a  subcompressed  tendon. 

Shape. — A  somewhat  thick  fasciculus. 

Relations. — Superiorly  with  the  tracheio-mastoideus,  inferiorly 
with  the  longus  colli  anterior,  and  externally  with  the  skin. 

Action. — Singly,  pulls  the  head  down  and  to  one  side;  acting  with 
its  fellow,  pulls  the  head  downwad. 

Tracheio-mastoideus  (Fig.  19,  No.  16).  (Synonym. — Longissi- 
mus  capitis  et  atlantis.) 

Location. — Laterally  on  the  anterior  portion  of  the  neck. 

Origin. — Semitendinous  from  the  diapophyses  of  the  second,  the 
third,  the  fourth,  and  the  fifth  cervical  vertebrae. 

Insertion. — By  subcompressed  tendon  to  the  base  of  the  cranium, 
at  the  outer  tubercle  of  the  basal  ridge  of  the  basi-temporal. 

Shape. — Flattened  from  side  to  side;  broad  at  the  posterior  por- 
tion, becomes  angular  at  the  anterior  portion. 

Action. — Singly,  pulls  the  head  down  and  to  one  side;  acting  with 
its  fellow,  pulls  the  head  downward. 

Interspinales  (Fig.  17,  A,  No.  2).  Location. — Superior  to  the 
vertebra. 

Origin  and  Insertion. — A  series  of  muscles  connecting  the  superior 
neural  spines  of  the  cervical  vertebrae. 

Shape.— Thin,  flat. 

Relations. — Anteriorly  the  posterior  border  of  the  vertebrae  in  front 
and  posteriorly  the  anterior  border  of  the  succeeding  vertebrae, 
inferiorly  by  the  vertebrae. 

Action. — To  approximate  the  spinous  portion  of  the  vertebrae. 

Interarticulares  (Fig.  17,  No.  A,  4).  Location. — Supero-laterally 
to  the  vertebrae.  Between  the  postzygapophysis. 

Origin  and  Insertion. — From  the  posterior  margin  of  the  ring  of 
the  atlas  to  the  postzygapophysis  of  the  axis.  Then  in  the  suc- 
ceeding vertebrae  from  the  postzygapophysis  of  the  vertebra  to 
the  same  of  the  succeeding  vertebra. 

Shape. — Muscular  bundle. 

Relations. — Inferiorly  with  the  vertebrae.  Supero-laterally  with 
the  obliquo-transversales. 

Action. — Aids  in  approximating  the  vertebrae  in  a  supero-lateral 
direction. 


86  ANATOMY   OF   THE   DOMESTIC   FOWL 

Obliquo-transversales  (Fig.  17, 'A,  No.  i).  Location.— Supero- 
lateral  to  the  vertebrae. 

Origin  and  Insertion.- — Passes  obliquely  from  the  transverse 
process  of  one  vertebra  to  the  postzygapophysis  of  the  vertebra 
beyond. 

Shape. — A  thin  fasciculus. 

Relations, — Inferiorly  with  the  interarticulares  and  laterally  with 
the  intertransversales. 

Action. — Aids  in  flexing  the  vertebrae  supero-laterally. 

Intertransversales  (Fig.  19,  No.  12).  Location — Laterally  to  the 
vertebrae. 

Origin  and  Insertion. — Extend  between  the  transverse  processes 
beginning  at  the  third  cervical  vertebra. 

Shape. — Short,  thick. 

Jfo/a/^ws.— Laterally  the  vertebrae.  Superiorly  the  obliquo- 
transversales. 

Action. — Aids  in  flexing  the  vertebrae  laterally. 

Scalenus  Medius  (Fig.  19,  No.  18).     (Synonym. — Scalenus.) 

Location. — Supero-laterally  to  the  entrance  of  the  thorax. 

Origin. — From  the  diapophysis  and  pleurapophysis  of  the  eleventh 
cervical  vertebra. 

Insertion. — To  the  entire  border  of  the  first  rib.  A  few  fibers 
pass  over  to  the  anterior  free  margin  of  the  middle  third  of  the 
second  rib. 

Shape. — Rather  pyramidal  in  shape  with  base  uppermost. 

Relations. — Posteriorly  with  the  levatores  costarum.  Internally 
with  the  longus  colli. 

Action. — When  the  first  rib  is  fixed  singly,  turns  the  neck  to  one 
side;  acting  with  its  fellow,  extends  the  neck.  When  the  neck  is 
fixed,  by  drawing  the  first  rib  forward,  it  acts  as  an  inspiratory 
muscle. 

THE  MUSCLES  OF  THE  AIR  PASSAGES 

The  Superior  Larynx 

Constrictor  glottidis  Thyreo-arytenoideus 

The  Inferior  Larynx 

Tracheo-lateralis  Broncho-trachealis  posticus 

Broncho-trachealis  anticus  Broncho-trachealis  brevis 

Bronchialis  posticus  Bronchialis  anticus  j 

Sterno-trachealis 


MYOLOGY  87 

Constrictor  Glottidis.  Location. — Supero-anterior  portion  of  the 
superior  larynx. 

Origin. — From  the  superior  and  longitudinal  line  of  the  thyroid 
plate. 

Insertion. — All  along  the  inner  margin  of  the  arytenoid  bone,  and 
to  the  apex  of  the  mid-cricoidal  segment. 

Shape. — Thin,  flat  sheet  extending  outward  and  upward,  and  then 
inward. 

Relation. — Inferiorly  with  the  larynx. 

Action. — The  two  muscles  of  this  kind  acting  together,  close  the 
glottis  by  drawing  the  apices  of  the  arytenoids  to  the  median  line. 

Thyreo-arytenoideus.  Location. — Supero-lateral  portion  of  the 
superior  larynx. 

Origin. — From  the  entire  outer  margin  of  the  thyroid  plate  and 
the  outer  margin  of  the  cricoid  bone. 

Insertion. — All  along  the  outer  margin  of  the  arytenoid  bone  and 
the  outer  border  of  the  central  cricoid  piece. 

Shape.— A  thin,  flat  sheet. 

Relations. — Infero-laterally  with  the  superior  larynx. 

Action. — The  two  muscles  of  this  kind  acting  together,  open 
the  glottis  by  pulling  the  arytenoid  bone  outward. 

Tracheo-lateralis  (Fig.  20,  No.  2).  Location. — Along  the  lateral 
side  of  the  trachea. 

Origin. — By  the  union  of  the  bronchio-trachealis  posticus  and 
bronchio-trachealis  anticus,  on  the  lateral  side  of  the  trachea, 
about  1^2  centimeters  from  the  bifurcation  of  the  trachea. 

Insertion. — In  delicate  fan-like  structure  to  the  side  of  the 
trachea,  near  the  superior  larynx. 

Shape. — Thin,  ribbon-shaped,  closely  attached  to  the  trachea. 

Relations. — Internally  with  the  trachea,  and  externally  with  the 
skin  and  other  integument. 

Action. — Acts  as  a  brace  to  the  sides  of  the  trachea,  and  contract- 
ing, approximates  the  tracheal  rings  and  thus  shortens  the  trachea. 

Broncho-trachealis  Posticus  (Fig.  2 1 ,  No.  3) .  Location. — Postero- 
superior  portion  of  the  trachea.  The  fibers  pass  downward  and 
backward. 

Origin. — From  the  inferior  end  of  the  tracheo-lateralis. 

Insertion. — To  the  end  of  the  third  half  of  the  bronchial  ring  of 
the  same  side. 

Shape. — A  small  fasciculus. 


88 


ANATOMY   OF   THE   DOMESTIC   FOWL 


Relations.  —Internally  with  the  trachea,  and  externally  with  the 
skin  and  other  integument. 


FIG.  20. — The  anterior  pectoral  region,  i,  Sterno-trachealis.  2,  Tracheo- 
lateralis.  3,  Broncho-trachealis  brevis.  4,  Costal  process  of  sternum.  5,  Right 
and  left  carotid  converging  and  occupying  same  sheath  at  6.  7,  The  heart 
showing  branches  of  coronary  artery.  8,  Cervical  air-sac.  9,  Left  brachio- 
cephalic  artery.  10,  Right  brachio-cephalic  artery,  n,  Trachea.  12,  Inferior 
larynx.  13,  Subclavian  artery.  14,  Carotid  trunk.  15,  Internal  thoracic 
artery.  i6,|Thyroid  gland.  17,  Anterior  vena  cava.  18,  Auricular  appendage. 


FIG.  21. — The  inferior  tracheal  region,     i,  Bronchialis  anticus.     2,  Bronchialis 
posticus.     3,  Broncho-trachealis  posticus.     4,  Broncho-trachealis  anticus. 

Action. — A  tensor  of  the  true  or  inferior  larynx. 
Broncho-trachealis  Anticus  (Fig.  21,  No,  4).    Location.-— Anterior 
portion  of  the  inferior  extremity  of  the  trachea. 


MYOLOGY  89 

Origin. — The  anterior  branch  of  the  bifurcated  tracheo-lateralis. 

Insertion. — To  the  anterior  extremity  of  the  third  half  ring  of  the 
bronchus  of  the  same  side. 

Shape. — A  small  fasciculus. 

Relations. — Internally  with  the  trachea,  and  externally  with  the 
skin  and  other  integument. 

Action. — A  tensor  of  the  inferior  larynx. 

Broncho-trachealis  Brevis  (Fig.  20,  No.  3).  Location.  —Posterior 
part  of  the  inferior  extremity  of  the  trachea. 

Origin. — From  just  beneath  the  broncho-trachealis  anticus  muscle. 

Insertion. — Extends  obliquely  across  the  inferior  larynx  and  is 
inserted  to  the  posterior  end  of  the  second  bronchial  ring. 

Shape. — Rather  short,  strong,  straight,  subcylindrical. 

'Relations. — Internally  with  the  trachea,  and  laterally  with  the 
broncho-trachealis  posticus. 

Action. — A  tensor  of  the  inferior  larynx. 

Bronchialis  Posticus  (Fig.  21,  No.  2).  Location. — Supero-lateral 
side  of  the  anterior  end  of  the  bronchi. 

Origin. — From  the  lateral  inferior  margin  of  the  last  tracheal  ring. 

Insertion. — Passing  obliquely  across  the  larynx  it  inserts  to  the 
posterior  extremity  of  the  second  half  ring  of  the  bronchus. 

Shape. — Small,  thick,  spindle-shaped. 

Relations. — Internally  with  the  trachea,  inferiorly  with  the  bron- 
chialis  anticus,  and  superiorly  with  the  broncho-trachealis  brevis. 

Action. — A  tensor  of  the  larynx. 

Bronchialis  Anticus  (Fig.  21,  No.  i).  Location. — Inferior  to  the 
former  muscle. 

Origin. — From  the  last  ring  of  the  trachea. 

Insertion. — The  fibers  pass  obliquely  forward  and  become  in- 
serted to  the  rim  of  the  arytenoid  cartilage  of  the  inferior  larynx, 
and  the  anterior  extremities  of  the  first  and  second  half  rings  of 
the  bronchus. 

Shape. — Thick,  spindle-shaped;  about  twice  the  size  of  the  bron- 
chialis  posticus. 

Relations. — It  is  crossed  at  its  origin  by  the  broncho-trachealis 
anticus  and  is  related  internally  with  the  bronchus  and  end  of  the 
trachea. 

Action. — -A  tensor  of  the  larynx. 

Sterno-trachealis  (Fig.  20,  No.  i).  Location. — The  inferior  re- 
gion of  the  trachea  above  the  above-named  muscles.] 


90  ANATOMY   OF   THE  DOMESTIC  FOWL 

Origin. — From  the  side  of  the  trachea  beneath  the  posterior  border 
of  the  broncho-trachealis  anticus. 

Insertion. — Passes  downward  and  backward  across  the  cavity  of 
the  chest  and  is  inserted  to  the  inner  part  of  the  costal  process  of  the 
sternum. 

Shape. — A  delicate  cord  of  fibers. 

Relations.- — Internally  with  the  broncho-trachealis  muscles. 

Action. — A  relaxor  of  the  larynx,  and  hence,  of  the  tympanic 
membrane. 

THE  STERNAL  GROUP 

Triangularis  Sterni.  Location. — In  the  floor  of  the  thoracic 
cavity. 

Origin. — From  the  entire  superior  margin  of  the  summits  of  the 
costal  processes. 

Insertion. — The  fibers  extend  upward  and  backward,  dividing  into 
four  digitations  which  cover  the  inner  surface  of  the  three  principal 
sternal  ribs,  and  are  inserted  to  the  first  four  as  high  as  their 
articulations  with  the  vertebral  ribs. 

Shape. — Flat  and  somewhat  triangular. 

Relations. — Inferiorly  with  the  floor  of  the  thoracic  cavity. 

Action. — A  powerful  muscle  of  expiration.  In  contracting,  les- 
sens the  cubic  content  of  the  thorax. 

The  Diaphragm  (Fig.  47,  No.  10;  Fig.  33,  No.  9).  Description. — 
The  diaphragm  in  the  domestic  fowl  is  rudimentary.  It  consists  of 
a  thin  semi-transparent  membrane,  situated  between  and  separating 
the  thoracic  and  the  abdominal  cavities.  It  readily  conforms  to  the 
various  organs  pressing  upon  it  from  each  side.  On  each  side  are 
three  rudimentary  muscles  which  extend  from  the  vertebral  heads  of 
the  second,  the  third,  and  the  fourth  sternal  ribs.  The  fibers  of 
these  muscles  spread  out  in  fan-like  upon  the  diaphragm,  and  are 
seen  just  above  the  digitations  of  the  triangularis  sterni. 

THE  ABDOMINAL  MUSCLES 

Obliquus  abdominis  externus         Obliquus  abdominis  internus 
Rectus  abdominis  Transversalis  abdominis 


Obliquus  Abdominis  Externus  (Fig.  22,  No.  i).    Location. — The 
outermost  muscle  of  the  lateral  abdominal  wall. 


MYOLOGY  91 

Attachments. — By  a  delicate  aponeurotic  membrane,  from  the  sides 
of  all  the  true  dorsal  ribs,  from  the  posterior  border  of  the  last  ver- 
tebral rib  and  the  adjoining  margins  of  the  pelvis,  and  from  the 
entire  posterior  surface  of  the  inferior  border  of  the  post-pubic 
element  of  the  pelvis;  by  aponeurosis,  blending  with  the  fascia  to- 
ward the  root  of  the  tail  and  lower  part  of  the  abdomen;  and  by 
aponeurosis  to  the  sides  of  the  sternum,  to  the  under  part  of  the 
pectoralis  major  muscle,  and  to  the  zyphoid  prolongation.  Also 
by  aponeurosis  it  meets  its  fellow  from  the  opposite  side,  at  the 
linea  alba. 


FIG.  22. — The  abdominal  muscles  of  a  hen.  Right  side,  i,  Obliquus  ab- 
dominis  externus.  2,  Obliquus  abdominis  internus.  3,  Peritoneum  covering 
intestines.  4,  Peritoneum  covering  the  gizzard.  5,  The  lungs  (note  how  small 
they  are  from  a  relative  standpoint).  6,  The  great  sciatic  or  ischiadic  nerve. 
7,  Lumbar  nerves.  8,  Kidney.  9,  Brachial  plexus.  10,  Pericardium  of  the 
base  of  the  heart,  n,  Anterior  vena  cava.  12,  Oil  gland.  13,  Showing  a 
sacculation  of  the  abdominal  muscles.  There  is  no  tunica  abdominalis  in  the 
fowl. 


Obliquus  Abdominis  Internus  (Fig.  22,  No.  2).  Location. — Just 
internal  with  regard  to  the  external  oblique. 

Attachments. — By  aponeurosis,  from  the  posterior  third  of  the 
post-pubic  element  of  the  pelvis;  by  muscular  fibers,  from  the  bal- 
ance of  the  bone;  and  by  a  few  fibers,  from  the  iliac  border  posterior 
to  the  acetabulum.  Anteriorly,  these  fibers  are  inserted  to  the 
entire  posterior  margin  of  the  last  vertebral  rib,  and  into  the  pleura- 
pophysial  head  of  the  last  costal  rib. 

Rectus  Abdominis  (Fig.  13,  No.  10  and  Fig.  23, No.  i).  Location. — 
The  inferior  median  abdominal  wall. 


92  ANATOMY   OF  THE  DOMESTIC  FOWL 

Attachments. — By  aponeurosis,  from  the  distal  extremity  of  the 
post-pubic  element  of  the  pelvis  and  from  the  semitendinous  liga- 
ment which  stretches  from  one  post-pubic  tip  to  the  other.  Attaches 
anteriorly  to  the  zyphoid  margin  of  the  sternum,  and  passes,  by  a 
broad  aponeurotic  membrane,  over  the  outer  surface  of  the  thoracic 
wall  beneath  the  external  oblique. 

Transversalis  Abdominis  (Fig.  25,  No.  H,  i).  Location. — Infero- 
lateral  portion  of  the  abdominal  wall. 

Attachments. — By  a  thin,  tendinous  attachment  from  the  entire 
post-pubic  and  iliac  margins  of  the  pelvis  and  from  the  interpubic 
ligament.  Its  fibers  cross  the  abdomen  between  the  peritoneum, 
the  rectum,  and  the  internal  oblique.  It  is  inserted  over  the  entire 
pleural  part  of  the  last  two  vertebral  ribs,  the  intercostal  muscles 
between  them,  and  the  same  surface  of  the  hemapophyses  connected 
below.  Inserts  into  the  linea  alba. 

Action. — The  abdominal  muscles  give  support  to  the  abdominal 
organs,  aid  in  flexing  the  spine,  draw  the  last  rib  backward,  thus 
aiding  in  respiration,  and  compress  the  abdominal  organs  to  aid 
in  defecation  and  expiration. 

THE  DORSO-LUMBAR  REGION 

Sacro-lumbalis  Longissimus  dorsi 


Sacro-lumbalis.    Location. — The  lateral  lumbo-sacral  region. 

Origin. — Tendinous  from  the  anterior  margin  of  the  ilium,  from  the 
angles  of  the  last  two  vertebral  ribs,  and  by  tendinous  slips,  from 
the  outer  ends  of  the  transverse  processes  of  the  last  three  dorsal 
vertebrae. 

Insertion. — By  a  few  fleshy  fibers  into  the  angle  of  the  first  dorsal 
rib  and  to  the  corresponding  points  upon  the  free  cervical  ribs, 
and  by  a  strong  semitendinous  insertion  into  the  outer  extremity  of 
the  diapophysis  of  the  twelfth  cervical  vertebra. 

Shape. — A  close  fitting,  tendo-muscular  sheet  extending  between 
the  anterior  margin  of  the  ilium  and  the  root  of  the  neck. 

Relations. — Intimately  blended  with  the  longissimus  dorsi  ex- 
ternally. 

Action. — Assists  the  longissimus  dorsi. 

Longissimus  Dorsi  (Fig.  24,  No.  4).  Location. — The  superior 
dorso-lumbar  region. 


MYOLOGY  93 

Origin. — From  the  inner  portion  of  the  anterior  margin  of  the 
ilium,  and  from  the  various  surfaces  afforded  by  its  walls  and  the 
walls  of  the  ilio-neural  canal;  by  a  series  of  short  and  distinct  ten- 
dons alternately  from  the  anterior  and  posterior  extremities  of  the 
summits  of  the  neural  spines  of  all  the  dorsal  vertebrae.  From  the 
diapophyses  of  the  dorsal  vertebrae,  from  the  crests  of  the  neural 
spines  of  the  last  three  dorsal  vertebrae,  from  the  bodies  of  the  dorsal 
vertebrae,  and  from  the  fascia  between  them  and  the  sacro-lumbalis; 
and  also  by  a  tendinous  sheet  continuous  with  the  origin  of  the  lon- 
gus  colli  posticus. 

Insertion. — By  four  fasciculi  into  the  free  posterior  margins  of 
the  oblique  processes  of  the  eleventh,  the  twelfth,  the  thirteenth, 
and  the  fourteenth  cervical  vertebrae. 

Shape. — A  large  flat  sheet. 

Relations. — Laterally,  with  the  superior  spinous  processes  of  the 
vertebrae,  and  with  the  superior  surface  of  the  ribs. 

Action. — Singly,  flexes  the  back  laterally;  with  its  fellow,  aids  in 
elevating  the  body  upward. 

THE  COCCYGEAL  MUSCLES 

Levator  coccygis  Levator  caudae 

Transversus  peronei  Depressor  caudae 

Depressor  coccygis  Lateralis  caudae 

Lateralis  coccygis  Inf  racoccygis 


Levator  Coccygis  (Fig.  23,  No.  2).  Location. — The  superior  part 
of  the  caudal  apparatus. 

Origin. — From  a  limited  area  of  the  ilium  just  beyond  and  to  the 
side  of  the  anterior  free  caudal  vertebrae. 

Insertion. — Into  the  tuberosity  of  the  anterior  margin  of  the 
pygostyle. 

Shape. — Short,  fleshy. 

Relations. — Superior  portion  of  the  coccygeal  vertebrae. 

Action. — Elevates  the  tail. 

Levator  Caudae  (Fig.  23,  No.  4).  Location. — Supero-lateral  side 
of  the  tail. 

Origin. — From  the  posterior  surface  of  the  post-acetabular  area  of 
the  pelvis,  and  from  the  superior  surface  of  all  the  coccygeal  ver- 
tebrae except  the  pygostyle. 


94 


ANATOMY   OF   THE  DOMESTIC  FOWL 


Insertion. — To  the  four  inner  quill  butts  of  the  main  tail  feathers. 

Shape. — Long,  spindle-shaped. 

Relations. — Internally,  with  the  levator  coccygis  and  externally, 
with  the  lateralis  caudae. 

Action. — Powerfully  elevates  the  four  inner  main  tail  feathers. 

Transversus  Peronei  (Fig.  23,  No.  3).  Location.— The  posterior 
abdominal  region. 


PIG.  23. — Outer  layer  of  muscles  of  the  tail  and  thigh,  i,  Rectus  abdominis. 
2,  Levator  coccygis.  3,  Transversalis  peronie.  4,  Levator  caudae.  5,  Lateralis 
caudas.  6,  Depressor  caudae.  7,  Sartorius.  8  and  9,  Gluteus  primus.  10, 
Semitendinosus.  n,  Gastrocnemius.  12,  Peroneus  longus.  13,  Flexor  per- 
foratus  indicis  secundus  pedis.  14,  Flexor  perforatus  medius  secundus  pedis. 
15,  Lateral  ligament  of  the  hock. 

Origin. — From  the  entire  posterior  margin  of  the  ischium,  and 
from  the  posterior  margin  of  the  post-pubis  extending  beyond  it. 

Insertion. — Becoming  aponeurotic,  it  passes  toward  the  coccyx 
and  is  attached  to  the  entire  posterior  margin  of  the  ilium.  Passes 
to  the  median  line,  meeting  its  fellow  in  front  of  the  anus. 

Shape.— Thin,  sheet-like. 


MYOLOGY  95 

Relations. — Infero-anteriorly  with  the  anus.  Posteriorly  with  the 
edges  of  the  ilium  and  of  the  ischium.  Internally  with  the  depressor 
caudae. 

Action.— Gives  support  to  the  viscera  in  the  post-anal  regleH^ 
and  aids  in  attaching  the  anus  to  the  structures  above. 

Depressor  Caudae  (Fig.  23,  No.  6).  Location. — The  infero-lateral 
side  of  the  tail. 

Origin. — From  the  lower  half  of  the  posterior  border  of  the  is- 
chium, and  from  the  entire  posterior  border  of  the  post-pubis  beyond. 

Insertion. — To  the  quill  butts  of  the  three  or  four  outer  main 
tail  feathers. 

Shape. — Strong,  conical. 

Relations. — -Externally,  with  the  depressor  coccygis. 

Action. — Singly,  pulls  the  tail  downward  and  outward;  with  its 
fellow,  pulls  the  tail  downward. 

Depressor  Coccygis.  Location. — The  outermost  of  the  infero- 
lateral  muscles  of  the  tail. 

Origin. — From  the  lower  half  of  the  posterior  margin  of  the  ischium 
and  the  anterior  three-fourths  of  the  posterior  margin  of  the  post- 
pubic  element  of  the  pelvis  beyond  it. 

Insertion. — To  the  thickened  rim  of  the  inferior  and  expanded 
portion  of  the  pygostyle. 

Shape. — Flat,  triangular. 

Relations. — Internally  with  the  depressor  caudae. 

Action. — Singly,  pulls  the  tail  downward  and  to  one  side;  with  its 
fellow,  pulls  the  tail  downward. 

Lateralis  Caudae  (Fig.  23,  No.  5).  Location. — The  lateral  side  of 
the  tail. 

Origin. — From  the  tip  of  the  transverse  process  of  the  first  free 
caudal  vertebrae. 

Insertion. — To  the  outer  three  quill  butts  of  the  main  tail  feathers. 

Shape. — Four  fasciculi  forming  a  fleshy  belly. 

Relations. — Inferiorly,  with  the  levator  caudae  and  superiorly  with 
the  depressor  caudae. 

Action.- — Singly,  pulls  the  tail  downward  and  outward;  with  its 
fellow,  pulls  the  tail  downward.  The  outermost  fasciculus  con- 
tracting, spreads  the  tail  feathers. 

Lateralis  Coccygis  (Fig.  2-5,  No.  E,  2).  Location. — The  infero- 
lateral  side  of  the  caudal  vertebrae. 

Origin. — From  the  surface  of  the  posterior  end  of  the  ilium  and  by 


g  ANATOMY   OF   THE  DOMESTIC  FOWL 

tendons  from  the  under  side  of  the  ends  of  the  first  three  or  four 
caudal  vertebrae. 

Insertion.  —  To  the  side  of  the  posterior  margin  of  the  expanded 
portion  of  the  pygostyle. 

Shape.  —  Subcompressed  mass. 

Relations.  —  With  the  transverse  processes  of  the  caudal  vertebra, 
inferiorly. 

Action.  —  Controls  the  lateral  movements  of  the  tail  and  its 
feathers,  and  the  oblique  downward  movement. 

Infracoccygis  (Fig.  25,  No.  E,  i).  Location.  —  The  extreme  in- 
ferior portion  of  the  caudal  vertebrae. 

Origin.  —  From  the  inferior  surface  of  the  diapophysis  of  the  last 
vertebra  which  anchyloses  with  the  pelvic  sacrum,  and  from  all  the 
free  caudal  vertebrae. 

Insertion.  —  Into  the  lower  side  of  the  pygostyle. 

Shape.  —  Flat,  somewhat  triangular. 

Relations.  —  Superiorly,  with  the  vertebrae,  laterally,  with  the 
lateralis  coccygis,  and  mesially,  with  its  fellow  of  the  opposite  side. 

Action.  —  Depresses  the  tail. 


THE  COSTAL  REGION 

Latissimus  dorsi  Trapezius 

Rhomboideus  Serratus  magnus  anticus 

Serratus  parvus  anticus  Teres  et  infraspinatus 

Intercostales  Levatores  costarum 

Appendico-costales 


Latissimus  Dorsi  (Fig.  24,  No.  7).  Location. — Supero-lateral  por- 
tion of  the  dorsal  region. 

Origin. — From  two  portions,  the  anterior  slip  from  the  outer  edge 
of  the  superior  margins  of  the  neural  spines  of  the  second  and  the 
third  dorsal  vertebrae,  and  the  second  portion  from  a  similar  point 
on  all  the  succeeding  dorsal  vertebrae.  The  second  portion  is  fascia- 
like  in  its  attachments. 

Insertion. — The  fibers  converge  toward  the  humerus  and  enter 
between  the  deltoid  the  scapular  head  of  the  triceps  and  the  re- 
maining heads  of  this  muscle  and  is  inserted  to  the  anconal  part 
of  the  humerus,  just  within  in  the  radial  crest. 


MYOLOGY  97 

Shape. — Thin,  triangular. 

Relations. — Superiorly,  with  the  skin.  The  most  superficial  of  the 
dorsal  muscles. 

Action. — To  elevate  the  humerus  and  thus  flex  the  shoulder-jomtr 
An  expiratory  muscle  when  the  wing  is  fixed. 

Trapezius  (Fig.  19,  No.  20).  Location. — In  the  shoulder  region, 
just  below  the  longissimus  dorsi. 

Origin. — From  the  neural  spines  of  the  second,  the  third,  the  fourth, 
and  the  fifth  cervical  vertebrae  just  below  the  latissimus  dorsi. 

Insertion. — To  the  mesian  upper  border  of  the  scapula. 

Shape. — A  flat  oblong  layer  of  fibers. 

Relations. — The  posterior  part  of  the  trapezius  overlies  the  an- 
terior part  of  the  rhomboideus.  The  posterior  two-thirds  is  covered 
by  the  latissimus  dorsi.  The  anterior  third  is  superficial. 

Action. — Draws  the  scapula  forward. 

Rhomboideus  (Fig.  19,  No.  19).  Location. — Supero-posterior 
scapular  region. 

Origin. — From  the  neural  spines  of  the  first  four  dorsal  vertebrae 
beneath  the  latissimus  dorsi  and  trapezius  muscles. 

Insertion. — The  fibers  passing  outward  and  backward  attach  to  the 
posterior  third  of  the  mesial  or  upper  border  of  the  scapula. 

Shape. — Thin,  flat,  delicate. 

Relations — Superiorly,  by  the  latissimus  dorsi  and  the  trapezius. 

Action. — To  draw  the  free  end  of  the  scapula  upward  and 
forward. 

Serratus  Magnus  Anticus  (Fig.  13,  No.  16).  Location. — The 
supero-lateral  side  of  the  thorax. 

Origin. — By  three  strong  digitations:  first,  from  the  outer  part  of 
the  second  true  rib  just  above  the  base  of  the  epineural  appendage; 
the  other  two,  from  similar  locations  on  the  two  succeeding  ribs, 
just  above  the  origin  of  the  dermo-ulnaris. 

Insertions. — The  first  by  tendinous  attachment  to  the  interpleura- 
pophysial  membrane.  The  rest  of  the  fibers  pass  upward  and 
slightly  forward,  and  are  inserted  to  the  inferior  surface  of  the 
apex  of  the  scapula. 

Shape. — Three  flat,  strong  digitations. 

Relations. — Internally,  with  the  ribs. 

Action. — If  the  scapula  is  fixed,  it  is  a  muscle  of  inspiration. 

Serratus  Parvus  Anticus.  Location. — The  outer  and  upper  sur- 
face of  the  anterior  part  of  the  thorax. 


98  ANATOMY   OF   THE   DOMESTIC   FOWL 

Origin. — By  three  digitations  from  the  outer  surface  of  the  first 
three  ribs  above  the  origin  of  the  serratus  magnus  anticus  and  the 
thoraco-scapularis. 

Insertion. — The  thin  sheet  of  fibers  passes  upward  and  backward, 
and  is  inserted  to  the  inferior  margin  of  the  scapula. 

Shape— Thin,  flat. 

Relations. — Internally,  with  the  ribs. 

Action. — If  the  scapula  is  fixed,  it  is  a  muscle  of  respiration. 

Teres  et  Infraspinatus  (Fig.  13,  No.  n).  Location. — Scapular 
region. 

Origin. — From  the  superior  surface  and  outer  margin  of  the  pos- 
terior two-thirds  of  the  scapula. 

Insertion. — The  fibers  pass  forward  and  outward,  and  insert  to  the 
humerus  at  the  middle  of  the  ulnar  margin  of  the  pneumatic  fossa, 
between  the  forks  of  the  triceps. 

Shape.  —Flat,  triangular-shaped. 

Relations. — Anteriorly,  with  the  supraspinatus.  Internally,  with 
the  ribs. 

Action. — Aids  in  keeping  the  humerus  in  its  socket.  Assists  in 
closing  the  wing  by  drawing  the  humerus  to  the  side  of  the  body. 

Intercostales  (Fig.  24,  No.  5).  Location. — Between  the  ribs  of  the 
upper  thoracic  region. 

Origin  and  Insertion.' — From  the  anterior  border  of  one  rib,  the 
fibers,  passing  obliquely  upward  and  forward,  and  the  lower  portion 
downward  and  forward,  are  inserted  to  the  posterior  border  of  the 
rib  just  in  front. 

Shape. — They  are  best  developed  in  the  anterior  portion  of  the 
thoracic  region  and  extend  down  as  far  as  the  sternal  ribs. 

Relations. — Internally  the  pleura,  and  anteriorly  and  posteriorly 
the  ribs. 

Action. — The  first  rib  being  rendered  fixed  by  the  scalenus  me- 
dius,  the  muscles  draw  the  ribs  forward,  thus  aiding  inspiration. 

Levatores  Costarum  (Fig.  24,  No.  2).  Location — Supero-lateral 
portion  of  the  thorax. 

Origin  and  Insertion. — A  series  of  muscles,  the  first  of  which 
extends  from  the  extremity  of  the  transverse  process  of  the  twelfth 
vertebra,  the  fibers  passing  downward  and  backward  to  the  anterior 
free  margin  of  the  upper  third  of  the  long  posterior  rib,  and  to 
the  external  surface  close  to  its  margin.  The  others  arise  and 
insert  in  a  similar  manner  from  the  ends  of  the  diapophyses  of  all 


MYOLOGY  .  99 

the  dorsal  vertebrae  and  attach  to  each  succeeding  rib.  Those  in 
front  are  best  developed. 

Shape, — Thin  and  triangular. 

Relations. — External  to  the  intercostales. 

Action. — Aids  in  respiration. 

Appendico-costales  (Fig.  24,  No.  i).  Location. — The  lateral  side 
of  the  thorax. 

Origin  and  Insertion. — From  the  posterior  edge  of  an  uncinate 
process  or  epineural  appendage,  the  fibers  extending  downward 
and  backward  to  the  outer  surface  of  the  succeeding  rib. 

Shape.- — A  series  of  thin  triangular-shaped  muscles. 

Relations. — Internally,  with  the  intercostales. 

Action. — Aids  in  respiration. 

THE  ANTERIOR  PECTORAL  GROUP 

Tensor  patagii  longus  Tensor  patagii  brevis 


Tensor Patagii Longus  (Fig.  15(7,  No.  i;  Fig.  14,  No.  2).  Loca- 
tion.— Anterior  shoulder  region,  in  the  triangular  patagium  of  the 
wing. 

Origin. — By  a  flat  tendon  common  to  it  and  the  tensor  patagii 
brevis  from  the  supero-mesial  line  of  the  head  of  the  clavicle. 

Insertion. — By  a  long  slender  tendon  extending  in  the  duplicature 
of  the  patagium,  with  which  the  fibers  blend.  Passing  to  the  side 
of  the  extensor  metacarpi  radialis  longus,  it  extends  over  the  end 
of  the  radius  and  is  inserted  to  the  os  carpi  radiale,  and  to  the  fascia 
which  binds  down  the  other  tendons  on  the  anterior  part  of  the  wrist- 
joint. 

Shape. — Cone-shaped  belly  terminating  in  a  long  tendon. 

Relations. — Externally,  with  the  skin;  by  its  tendon,  with  the 
border  of  the  extensor  metacarpi  radialis  longior. 

A  ction  — ^Tenses  the  soft  part  in  the  fold  of  the  wing,  and  aids  in 
flexing  the  forearm. 

Tensor  Patagii  Brevis  (Fig.  14,  No.  3).  Location. — In  the  trian- 
gular patagium  of  the  wing. 

Origin. — From  the  head  of  the  clavicle  in  common  with  the 
preceding. 

Insertion. — The  tendon  bifurcates,  one  branch  blending  with  the 
fascia  of  the  extensor  metacarpi  radialis  longior,  the  other  inserting 
just  below  the  tubercle  on  the  external  condyle  of  the  humerus. 


100  .  ANATOMY   OF   THE   DOMESTIC   FOWL 

Shape. — Fleshy;  somewhat  broader  and  longer  than  the  preceding. 

Relations. — Inferiorly,  with  the  preceding. 

Action.- — Assists  the  tensor  patagii  longus  in  flexing  the  forearm. 

THE  PECTORAL  MUSCLES 

Pectoralis  major  Pectoralis  secundus 

Pectoralis  tertius 


Pectoralis  Major  (Fig.  13,  No.  5).  Location. — On  the  lateral 
side  of  the  sternum. 

Origin. — From  the  posterior  portion  of  the  lateral  wing  of  the 
sternal  body,  from  the  outer  marginal  third  of  the  keel  of  the 
sternum,  and  from  the  entire  outer  side  of  the  limb  of  the  furcula  or 
clavicle. 

Insertion. — The  fibers  converging  form  toward  the  proximal 
third  of  the  humerus  a  broad  tendon  which  by  its  insertion  covers  the 
entire  palmar  part  of  the  pectoral  crest.  A  few  of  the  tendinous 
fibers  pass  over  the  shoulder-joint  and  blend  with  the  long  head  of 
the  biceps.  Near  this  point  it  receives  the  insertion  of  the  dermo- 
humeralis. 

Relations. — Inferiorly,  with  the  skin;  superiorly,  in  the  sternal 
region,  with  the  pectoralis  secundus  and  the  pectoralis  tertius. 

Shape. — Fleshy;  largest  of  the  pecto rales. 

Action. — Powerfully  depresses  the  humerus.  The  chief  muscle 
of  flight. 

Pectoralis  Secundus  (Fig.  13,  No.  9;  Fig.  15,  No.  A,  6).  Lo- 
cation.— The  entire  lateral  side  of  the  sternum. 

Origin. — From  the  anterior  sternal  extremity  of  the  lower  third 
of  the  .coracoid,  from  the  keel  and  sternal  wing,  and  by  a  tendon 
from  a  membraneous  expansion  between  the  coracoid  and  the 
clavicular  bones  and  from  the  lower  third  of  the  coracoid. 

Insertion. — The  fibers  converge  into  a  tendon,  which  passes  up- 
ward around  the  coracoid  to  its  posterior  through  a  canal  formed  by 
the  scapula,  the  coracoid,  and  the  clavicle,  the  foramen  triosseum 
(Fig.  15,  No.  -4,7).  This  tendon  then  passes  outward  and  downward, 
and  becoming  flat,  inserts  to  the  humerus  just  anterior  to  the  radial 
crest  and  nearer  to  the  humeral  head  than  does  the  pectoralis  major. 

Relations.- — Internally,  with  the  breast-bone;  externally,  with  the 
pectoralis  major;  and  superiorly,  with  the  pectoralis  tertius. 


MYOLOGY  j   —    101 


Shape. — Long,  fusiform,  fleshy.  *       -^  \     •  •// 

Action. — Raises  the  wing. 

Pectoralis  Tertius  (Fig.  13,  No.  6;  Fig.  15,  No.  ^4,  5).  Location. — 
On  the  antero-lateral  side  of  the  sternum. 

Origin. — From  the  anterior  half  of  the  exterior  of  the  body  of 
the  sternum,  from  the  fascia  of  the  subclavius  on  the  outer  border 
of  the  costal  process,  and  from  the  outer,  lower  third  of  the 
coracoid  process. 

Insertion. — The  fibers  pass  upward  to  the  outer  side  of  the  coracoid, 
and  becoming  tendinous  as  they  reach  the  humerus,  by  a  strong, 
flattened  tendon  insert  to  the  ulnar  crest  of  the  humerus  on  the 
proximal  margin  at  about  a  middle  point  of  the  pneumatic  fossa. 

Relations. — Externally,  with  the  pectoralis  major;  inferiorly, 
with  the  pectoralis  secundus;  internally,  with  the  fascia  of  the  sub- 
clavius and  the  sternum. 

Shape. — Fleshy,  fusiform. 

A  ction.— Assists  the  pectoralis  secundus  in  elevating  the  humerus. 

MUSCLES  OF  THE  SCAPULAR  REGION 

Coraco-humeralis  Scapulo-humeralis 

Supraspinatus  Subclavius 

Coraco-brachialis  Teres  minor 

Levator  scapulae  Thoraco-scapularis 

Subscapularis 


Coraco-humeralis.    Location. — The  scapulo-humeral  region. 

Origin. — From  the  outer  side  of  the  head  of  the  coracoid,  supero- 
laterally  to  the  long  head  of  the  biceps. 

Insertion. — To  the  palmar  part  of  the  head  of  the  humerus  just 
inside  of  the  insertion  of  the  pectoralis  major. 

Shape. — A  delicate  subcylindrical  muscle. 

Relations. — Superior  to  the  head  of  the  humerus. 

Action. — Aids  in  extending  the  humerus. 

Scapulo-humeralis  (Fig.  14,  No.  10).  Location.— The  scapulo- 
humeral  region. 

Origin. — From  the  inner  side  of  the  neck  of  the  scapula  just  within 
the  head  of  the  deltoid. 

Insertion. — Passing  over  the  top  of  the  shoulder-joint  it  is  inserted 
to  the  palmar  part  of  the  humeral  head  between  the  insertion  of 
the  pectoralis  major  and  the  pectoralis  secundus. 


102  :  ANATOMY   OF   THE   DOMESTIC   FOWL 


.-^- Narrow,,  flat  ribbon. 

Relations.— Along  the  upper  margin  of  the  larger  portion  of  the 
deltoid. 

Action. — Aids  in  extending  the  humerus. 

Supraspinatus   (Fig.    19,  No.    22).    Location. — Scapular  region. 

Origin. — From  the  superior  surface  and  outer  third  of  the  scapula. 

Insertion. — To  the  lower  border  of  the  pneumatic  fossa  of  the 
humerus. 

Shape. — Thin,  flat,  triangular. 

Relations. — Externally,  with  the  trapezius  and  posteriorly,  with 
the  teres  et  infraspinatus. 

Action. — If  the  scapula  is  the  fixed  point  it  will  pull  the  humerus 
upward  and  backward. 

Subclavius.    Location. — Anterior  sternal  region. 

Origin. — From  the  entire  outer  surface  of  the  sternal  process  of 
the  sternum  and  the  adjacent  outer  surfaces  of  three  or  four  of 
the  hemapophyses. 

Insertion. — To  the  inferior  margin  of  the  coracoid  bone,  the  longer 
fibers  passing  over  to  the  fossa  in  the  lower  third  of  the  posterior 
part  of  the  coracoid. 

Shape. — Rather  small,  fleshy. 

Relations. — Overlapped  by  the  pectoralis  tertius. 

Action. — Pulls  the  coracoid  outward.  Also  aids  in  keeping  the 
coracoid  in  place. 

Coraco-brachialis  (Fig.  13,  No.  15).  Location. — Along  the  cora- 
coid shaft. 

Origin. — By  a  delicate  tendon  from  a  small  circular  point  on  the 
postero-mesial  part  of  the  shaft  of  the  coracoid  immediately  above 
the  attachment  of  the  subclavius  and  the  fossa  at  that  point. 

Insertion. — To  the  top  of  the  ulnar  tuberosity  of  the  humerus. 
This  subcircular  space  is  common  to  the  teres  minor  and  to  this 
muscle. 

Shape. — Long,  fusiform. 

Relations. — With  the  shaft  of  the  coracoid  between  the  teres 
minor  and  subscapularis. 

Action. — To  depress  the  wing. 

Teres  Minor  (Fig.  13,  No.  14).  Location. — The  coraco-scapular 
region. 

Origin. — From  under  the  side  of  the  anterior  tip  of  the  scapula. 

Insertion. — Passing   outward  behind  the  coracoid  head  and  be- 


MYOLOGY  103 

neath  the  neck  of  the  scapula,  it  is  attached  by  a  small  tendon  to 
the  top  of  the  ulnar  tuberosity  of  the  humerus  in  common  with  the 
coraco-brachialis,  with  which  tendon  it  fuses. 

Shape. — Small,  chunky. 

Relations. — Anteriorly,  with  the  tip  of  the  scapula  and  behind  the 
coracoid  head.  Posteriorly,  with  the  coraco-brachialis. 

Action. — Aids  in  the  downward  stroke  of  the  wing. 

Levator  Scapulae.    Location:—  Scapular  region. 

Origin. — By  two  strong  digitations,  one  from  each  of  the  lateral 
processes  of  the  first  cervical  vertebra. 

Insertion. — To  the  middle  third  of  the  inferior  part  of  the  blade 
of  the  scapula. 

Shape. — Small  and  flat. 

Relations. — Inferior  to  the  scapula. 

Action. — Pulls  the  scapula  forward,  and  with  it  the  entire  shoulder 
girdle,  which  articulates  like  a  hinge-joint  at  the  costo-sternal 
juncture. 

Thoraco-scapularis.    Location.— Lateral  side  of  the  chest. 

Origin. — From  the  outer  part  of  the  lower  half  of  the  first  free 
rib,  the  outer  side  of  the  next  succeeding  rib  and  its  epineural  append- 
age, and  from  a  similar  surface  on  the  next  rib. 

Insertion. — By  a  broad,  flat  tendon  which  passes  between  the 
two  divisions  of  the  subscapularis  and  inserts  at  a  point  at  the 
juncture  of  the  anterior  and  middle  third  of  the  outer  margin  of 
the  scapula. 

Shape. — Broad,  flat. 

Relations. — Internally,  with  the  ribs  and  the  scapula. 

Action. — When  the  scapula  is  fixed  it  is  a  muscle  of  inspiration. 
When  the  ribs  are  fixed,  it  draws  the  scapula  downward.  . 

Subscapularis.    Location. — Scapulo-humeral  region. 

Origin. — From  the  anterior  and  outer  half  of  the  scapula. 

Insertion. — By  a  strong  and  subcylindrical  tendon  to  the  top  of 
the  ulnar  tuberosity  of  the  humerus  close  to  the  combined  tendons 
of  the  coraco-brachialis  and  teres  minor. 

Shape. — A  large  and  powerful  muscle. 

Relations. — The  flat  tendon  of  the  thoraco-scapularis  divides  the 
posterior  portion  of  the  belly  into  two  portions. 

Action. — A  powerful  rotary  muscle  of  the  head  of  the  humerus; 
aids  in  keeping  the  humeral  head  in  the  glenoid  cavity. 


104  ANATOMY    OF   THE   DOMESTIC   FOWL 

THE  MUSCLES  OF  THE  BRACHIAL  REGION 

Biceps  Triceps 

Deltoid  Brachialis  anticus 


Biceps  (Fig.  13,  No.  8).     (Synonym. — Biceps  brachii.) 

Location. — The  anterior  brachial  region. 

Origin. — By  a  broad  tendon  it  covers  the  top  of  the  shoulder- 
joint,  dividing  into  two  heads,  giving  rise  to  the  long  and  the  short 
heads.  The  long  is  inserted  into  the  outer  part  of  the  head  of  the 
coracoid  just  beyond  the  glenoid  cavity;  the  short  head  to  the 
distal  angle  of  the  ulnar  tuberosity  of  the  humerus. 

Insertion. — To  the  ulna  just  in  front  of  the  articular  cavity  for 
the  trochlear  surface  of  the  distal  extremity  of  the  humerus. 

Shape. — Large,  subfusiform. 

Relations.' — On  one  side  by  the  triceps  and  the  other  the  deltoid 
and  anteriorly  partially  covered  by  the  patagii  muscles. 

Action. — A  powerful  flexor  of  the  forearm. 

Deltoid  (Fig.  13,  No.  12;  Fig.  15,  No.  8).  Location. — Occupying 
the  lateral  side  of  the  humerus;  the  brachial  region. 

Origin. — Divided  into  two  portions,  the  long  narrow  head  extends 
from  the  clavicular  process  of  the  scapula  and  from  the  adjacent 
surface  of  the  same  bone.  These  fibers  then  extend  around  the  back 
of  the  shoulder-joint,  and  are  joined  by  the  fibers  that  arise  from 
the  entire  outer  surface  of  the  large  os  humero-scapulare.  These 
latter  fibers  are  inserted  upon  an  extensive  area  upon  the  anconal 
part  of  the  bone  beyond  the  humeral  articular  head,  and  to  almost 
the  entire  shaft  below  it. 

Insertion. — By  a  subcylindrical  tendon  to  the  proximal  side  of  the 
tubercle  of  the  external  condyle,  and  above  the  insertion  of  the 
extensor  metacarpi  radialis  longus. 

Shape. — Large,  fleshy,  with  tendinous  attachment. 

Relations. — On  one  side  by  the  biceps  and  the  other  by  the  triceps 
also  the  patagii. 

Action. — To  extend  the  arm. 

Triceps  (Fig.  15,  No.  7).     (Synonym. — Triceps  brachii.) 

Location. — The  posterior  humeral  region. 

Origin. — By  three  portions:  by  the  internal  and  external  heads, 
and  by  the  long  scapular  head.  The  internal  and  the  external 
heads  are  blended  except  at  their  proximal  extremities.  Each  head 
arises  from  the  anconal  surface  of  the  shaft  of  the  humerus.  The 


MYOLOGY  105 

internal  head  being  located  toward  the  deltoid  attachment  and  the 
external  head  into  the  pneumatic  fossa.  The  long  head  extends 
from  a  circumscribed  area  just  posterior  to  the  glenoid  cavity  of  the 
scapula.  The  fibers  pass  around  the  shoulder-joint,  beneath  ~the 
deltoid. 

Insertion. — The  broad  tendon  passes  over  the  elbow- joint  and  is 
inserted  to  the  entire  under  surface  of  the  olecranon  of  the  ulna. 

Shape — Long,  large,  fleshy. 

Relations. — The  supraspinatus  passes  between  the  internal  and  the 
external  heads.  It  is  bounded  by  the  biceps  and  the  deltoid. 

Action. — An  extensor  of  the  antibrachial  region  directly  antago- 
nizing the  biceps. 

Brachialis  Anticus  (Fig.  15,  No.  9;  Fig.  14,  No.  5).  Location. — 
In  the  flexure  of  the  humerus  and  the  ulna. 

Origin. — It  arises  fleshy  from  a  circumscribed  area  on  the  inner 
side  of  the  anconal  part  of  the  distal  extremity  of  the  humerus. 

Insertion. — The  fibers  passing  directly  over  the  elbow-joint  become 
inserted  to  the  lateral  surface  of  the  proximal  end  of  the  ulna  close 
to  the  margin  of  the  sigmoid  cavity. 

Shape. — Small,  fleshy. 

Relations — With  the  joint. 

Action. — Assists  in  flexing  the  forearm  upon  the  arm.  Protects 
the  structures  in  the  anterior  part  of  the  elbow-joint. 

THE  MUSCLES  OF  THE  FOREARM  AND  THE  HAND 

Extensor  metacarpi  radialis  longior  Extensor  digitorum  communis 

Supinator  brevis  Flexor  metacarpi  radialis 

Pronator  brevis  Pronator  longus 

Extensor  ossis  metacarpi  pollicis  Anconeus 

Extensor  indicis  longus  Flexor  digitorum  sublimis 

Flexor  digitorum  profundus  Flexor  carpi  ulnaris 
Flexor  carpi  ulnaris  brevior 


Extensor  Metacarpi  Radialis  Longior  (Fig.  1 3 ,  No.  1 7) .  Location. — 
Superior  to  the  radius. 

Origin — By  two  strong  tendinous  heads;  the  outer  from  the  tuber- 
cle of  the  external  condyle  of  the  humerus,  just  above  the  origin  of 
the  tendon  of  the  tensor  patagii  brevis;  the  inner  and  stronger 


106  ANATOMY   OF   THE   DOMESTIC   FOWL 

portion  from  the  tubercle  found  above  the  oblique  trochlear  facet 
of  the  distal  end  of  the  radius. 

Insertion. — Becoming  a  flat,  broad,  and  strong  tendon  at  about  the 
middle  of  the  forearm,  finally  becomes  inserted  to  the  apex  of  the 
anchylosed  first  metacarpal  of  the  carpo-metacarpus. 

Shape. — A  thick,  fusiform  belly,  tendinous  at  both  extremities. 

Relations. — By  the  side  of  the  pronator  brevis. 

Action. — Raises  the  hand,  and  draws  it  forward  toward  the  radial 
margin  of  the  forearm  and  retains  it  on  the  same  side. 

Extensor  Digitorum  Communis  (Fig.  15,  No.  2).  Location. — The 
upper  metacarpal  region. 

Origin. — Immediately  below  the  tubercle  of  the  external  condyle 
of  the  humerus. 

Insertion. — By  a  small  tendon  to  the  outer  side  of  the  base  of  the 
pollex,  and  at  a  mid-point  upon  the  anterior  rim  of  the  proximal 
phalanx  of  the  middle  finger. 

Shape. — Small  spindle-shaped,  becoming  tendinous  at  about  the 
middle  of  the  forearm. 

Relations. — Occupies  the  middle  of  the  group  of  muscles  on  the 
outer  side  of  the  forearm. 

Action. — An  extensor  of  the  digit. 

Supinator  Brevis  (Fig.  14,  No.  7).  Location. — The  superior  part 
of  the  radius. 

Origin. — From  the  external  condyle  of  the  humerus  below  the 
origin  of  the  tendon  of  the  extensor  digitorum  communis. 

Insertion. — To  the  outer  side  of  the  shaft  of  the  radius,  for  nearly 
one-third  of  its  length. 

Shape. — Thin,  slender.  , 

Relations. — Inferiorly,  with  the  bone. 

Action. — A  supinator  of  the  radial  region,  and  antagonistic  to  the 
pronators. 

Flexor  Metacarpi  Radialis  (Fig.  15,  No.  10).  Location. — The  low- 
est of  the  group  of  three  muscles  on  the  outer  part  of  the  forearm. 

Origin. — By  two  tendinous  heads,  the  longer  from  the  external 
condyle  of  the  humerus,  and  the  other  just  beyond  the  base  of  the 
olecranon. 

Insertion. — Becomes  tendinous  at  about  the  middle  of  the  shaft 
of  the  ulna  and  inserts  to  a  prominent. process  on  the  proximal 
third  of  the  posterior  part  of  the  shaft  of  the  mid-metacarpal. 

Shape. — Fusiform. 


MYOLOGY  107 

Relations. — Inferiorly,  the  anconeus  and  superiorly,  the  extensor 

gitorum  communis. 

Action. — A  powerful  flexor  of  the  hand. 

Pronator  Brevis    (Fig.    13,   No.   18).    Location. — Supero-Iaterar- 
side  of  the  forearm. 

Origin. — From  just  above  the  internal  condyle  of  the  humerus: 

Insertion. — The  tendon  passing  obliquely  across  the  interosseous 
space  and  is  inserted  to  the  ulnar  side  of  the  shaft  of  the  radius, 
just  beyond  the  juncture  of  the  proximal  and  the  middle  thirds. 

Shape. — Fusiform. 

Relations. — Superior  to  the  pronator  longus. 

Action. — Pronates  the  forearm,  and  flexes  the  forearm  upon  the 
arm. 

Pronator  Longus  (Fig.  14,  No.  6).    Location.— Lateral  side  of  the 
— ^/  radio-ulnar  region. 

Origin. — From  the  middle  of  the  internal  condyle  of  the  humerus. 

Insertion. — To  the  shaft  of  the  radius  just  beneath  the  pronator 
brevis. 

Shape. — Massive,  ellipsoidal. 

Relations. — Between  the  pronator  brevis  and  flexor  digitorum 
profundus. 

Action. — A  pronator. 

/  Extensor  Ossis  Metacarpi  Pollicis  (Fig.  13,  No.  23).    Location. — 
Slightly  interposed  between  the  ulna  and.  radius. 

Origin. — Immediately  in  front  of  the  greater  sigmoid  cavity  of  the 
ulna. 

Insertion. — To  the  palmar  side  of  the  base  of  the  first  metacarpal 
in  common  with  the  extensor  metacarpi  radialis  longior. 

Shape. — Delicate,  straight. 

Relations. — Superiorly,  the  extensor  indicis  longus,  and  inferiorly, 
the  anconeus  and  the  flexor  digitorum  profundus. 

Action. — Extends  the  hand  upon  the  forearm. 

Anconeus  (Fig.  15,  No.  4).  Location. — Between  the  ulna  and  the 
radius. 

Origin. — By  a  short,  strong,  subcylindrical  tendon  from  the  lower 
posterior  of  the  external  condyle  of  the  humerus. 

Insertion. — To  the  latero-radial  side  of  the  ulna  somewhat  beyond 
its  middle. 

Shape. — Fusiform. 


J 


IO8  ANATOMY   OF   THE   DOMESTIC   FOWL 

Relations. — Superiorly,  the  extensor  indicis  longus,  and  inferiorly, 
the  ulna. 

Action. — A  flexor  of  the  forearm. 

Extensor  Indicis  Longus  (Fig.  13,  No.  22;  Fig.  15,  No.  13).  Lo- 
cation.— Infero-lateral  to  the  radius. 

Origin. — From  about  one-half  the  surface  of  the  proximal  portion 
of  the  radius. 

Insertion. — Possesses  a  long  tendon  which  passing  over  a  groove  at 
the  distal  end  of  the  ulna  and  receiving  muscular  fibers  at  the  base 
of  the  metacarpus,  extends  down  the  anterior  part  of  the  hand 
and  is  inclosed  in  a  sheath  in  front  of  the  superior  part  of  the  first 
phalanx  of  the  index-finger.  This  tendon  is  inserted  into  the  an- 
terior upper  rim  of  the  distal  phalanx. 

Shape. — Small,  thin. 

Relations. — Supero-laterally  with  the  radius. 

Action. — Extensor  of  the  digit. 

Flexor  Digitorum  Sublimis.    Location. — The  forearm. 

Origin. — From  the  internal  condyle  of  the  humerus. 

Insertion. — Passing  over  the  wrist,  it  is  inserted  to  the  middle 
phalanx  of  the  hand. 

Shape. — A  musculo-tendinous  band,  "rather  delicate  and  rudi- 
mentary. 

Relations. — Closely  adhering  to  the  integument  that  stretches  from 
the  internal  condyle  of  the  humerus  to  the  wrist. 

Action. — Assists  these  muscles.     A  flexor. 

Flexor  Digitorum  Profundus  (Fig.  13,  No.  21).  Location  — 
Lateral  side  of  the  ulna. 

Origin. — By  two  heads  from  the  proximal  extremity  of  the  ulna, 
between  which  the  brachialis  anticus  passes. 

Insertion. — The  two  bellies  uniting  are  attached  to  the  under 
side  of  the  shaft  of  the  ulna.  It  becomes  tendinous  about  the  middle 
of  the  shaft,  and  inserts  to  the  ulnar  side  of  the  base  of  the  distal 
joint  of  the  index-finger. 

Shape. — A  fleshy  belly  with  long  tendon. 

Relations. — Inferiorly,  with  the  flexor  carpi  ulnaris,  superiorly, 
with  the  pronator  brevis. 

Action. — A  flexor  of  the  digit. 

Flexor  Carpi  Ulnaris  (Fig.  13,  No.  19).  Location.— Inferior  part 
of  the  forearm. 

Origin. — By  two  strong  tendons;  one  from  the  side  and  posterior 


MYOLOGY 

of  the  internal  condyle  of  the  humerus,  passing  through  the  humero- 
ulnar  pulley  at  the  side  of  the  base  of  the  olecranon  process;  the 
other,  to  the  posterior  of  the  internal  condyle  of  the  humerus.  It 
does  not  pass  through  a  pulley. 

Insertion. — A  subcylindrical  tendon  extends  back  of  the  ulnare 
ossicle  of  the  carpus  giving  off  a  tendinous  slip  to  the  flexor  digi- 
torum  profundus,  and  becomes  inserted  to  the  anterior  rim  of  the 
proximal  phalanx  of  the  index  digit.  It  has  an  attachment  at 
the  carpus. 

Shape. — A  strong  fleshy  belly  terminating  in  a  long  tendon. 

Relations. — The  outermost  inferior  muscle  of  the  forearm. 

Action. — A  powerful  flexor  of  the  hand  upon  the  forearm. 

Flexor  Carpi  Ulnaris  Brevior  (Fig.  13,  No.  20).  Location. — 
Inferior  part  of  the  antibrachial  region. 

Origin. — From  a  broad  area  on  the  middle  third  of  the  upper  side 
of  the  shaft  of  the  ulna. 

Insertion. — Near  the  top  of  the  outer  edge  of  the  anchylosed 
os  magnum  of  the  carpo-metacarpus. 

Shape. — Thin,  somewhat  flat. 

Relations. — To  the  inside  of  the  flexor  digitorum  profundus. 

Action. — Flexes  the  hand  upon  the  forearm  and  rotates  the  hand 
toward  the  body. 

OTHER  MUSCLES  OF  THE  DIGITS 

Extensor  proprius  pollicis  Flexor  brevis  pollicis 

Flexor  minimi  digiti  Flexor  minimi  digiti  brevis 

Abductor  minimi  digiti  Interosseous  dorsalis 

Interosseous  palmaris  Flexor  metacarpi  brevis 


Extensor  Proprius  Pollicis   (Fig.  13,  No.  2pa).    Location. — An- 
terior to  the  radio-carpal  joint. 

Origin. — From  the  ulnar  side  of  the  tendon  of  the  extensor  meta- 
carpi radialis  longior. 

Insertion. — To  the  antero-ulnar  side  of  the  pollex. 

Shape. — Small,  spindle-shaped;  tendinous  at  both  attachments. 

Relations. — Inferiorly,  with  the  proximal  and  anterior  part  of  the 
metacarpus. 

Action. — An  extensor  of  the  pollex. 

Flexor  Brevis  Pollicis  (Fig.  13,  No.  28a).    Location. — Anterior  to 
the  pollex. 


110  ANATOMY   OF   THE  DOMESTIC  FOWL 

Origin. — From  the  shaft  of  the  mid-metacarpal  bone,  just  below 
the  pollex. 

Insertion. — Distal  apex  of  the  pollex. 

Shape. — Short,  small,  fleshy. 

Relations. — Superiorly,  with  the  inferior  part  of  the  pollex. 

Action. — Flexes  the  pollex. 

Flexor  Minimi  Digiti.    Location. — Inferior  side  of  the  metacarpus. 

Origin. — From  the  posterior  part  of  the  median  metacarpal  close 
to  the  os  carpi  ulnare.  A  few  fibers  extend  to  the  ulna. 

Insertion. — Into  the  base  of  the  median  phalanx. 

Shape. — Small,  slender,  short. 

Relations. — Superiorly,  with  the  metacarpal  bone. 

Action. — A  flexor  of  the  digit. 

Flexor  Minimi  Digiti  Brevis  (Fig.  13,  No.  30).  Location. — In- 
ferior to  the  third,  or  small  finger. 

Origin. — From  the  lower  and  posterior  end  of  the  median  meta- 
carpal and  from  the  adjacent  tendon  of  the  preceding. 

Insertion. — Inserted  to  the  apex  of  the  small  finger. 

Shape. — Small  and  rather  rudimentary. 

Relations— ^Inferior  to  the  small  finger. 

Action. — Acts  as  a  posterior  ligament  of  this  joint. 

Abductor  Minimi  Digiti.  Location. — Supero-lateral  side  of  the 
small  finger. 

Origin. — From  the  proximal  extremity  of  the  anterior  aspect  of  the 
third  finger. 

Insertion. — To  the  posterior  border  of  the  proximal  phalanx  of 
the  second,  or  index-finger  at  a  point  just  above  the  tip  of  the  third 
finger. 

Shape. — A  few  muscular  fibers  with  some  tendinous  material. 

Relations. — At  the  base  of  the  median  segment  of  the  index-finger 
and  to  the  side  of  the  third. 

Action. — Antagonizes  the  powerful  flexors  on  the  back  of  the 
joint. 

Interosseus  Dorsalis  (Fig.  13,  No.  31).  Location. — By  the  side 
of  the  metacarpus. 

Origin. — From  the  margin  of  the  shaft  of  the  median  metacarpal. 

Insertion. — To  the  anterior  part  of  the  base  of  the  distal  phalanx 
of  the  index  digit. 

Shape. — Short,  delicate,  with  long  tendon. 

Relations. — Internally,  the  metacarpal  bone. 


MYOLOGY  III 

Action. — Extends  the  last  bone  of  the  middle  finger. 

Interosseus  Palmaris  (Fig.  13,  No.  32).  Location. — On  the 
opposite  side  of  the  bone  from  the  interosseous  dorsalis. 

Origin. — From  the  shaft  of  the  median  metacarpal  under~lEe 
preceding. 

Insertion.  —To  the  apex  of  the  last  joint  of  the  second,  or  middle 
finger. 

Shape. — Small,  delicate,  with  long  slender  tendon. 

Relations. — Beneath  the  preceding  and  along  the  metacarpal  bone. 

Action. — Flexes  the  terminal  phalanx. 

Flexor  Metacarpi  Brevis.  Location. — To  the  lateral  side  of  the 
metacarpal  bone. 

Origin. — From  the  outer  side  of  the  distal  extremity  of  the  ulna. 

Insertion.— To  the  base,  in  front,  and  on  the  ulnar  side  of  the 
proximal  phalanx  of  the  index  digit. 

Shape. — Delicate,  with  long  slender  tendon. 

Relations. — On  the  lateral  side  of  the  ulna  and  the  metacarpal 
bone. 

Action. — Flexes  the  metacarpus. 

MUSCLES  OF  THE  POSTERIOR  LIMB 

Sartorius  Gluteus  primus 

Gluteus  medius  Gluteus  minimus 

Extensor  femoris  Vastus  internus 

Biceps  flexor  cruris  Semitendinosus 

Semitendinosus  accessorius  Semimembranosus 

"  Femoro-caudal  Obturator  externus      t 

Obturator  internus  Gemellus 

Abductor  longus  Adductor  magnus 


Sartorius  (Fig.  23,  No.  7).  Location. — Extreme  anterior  portion 
of  the  thigh. 

Origin. — From  the  outer  two-thirds  of  the  superior  surface  of  the 
raised  emarginations  of  the  anterior  border  of  the  ilium,  and  by 
fascia  from  the  neural  spines  of  the  fourth  dorsal  vertebra. 

Insertion. — Obliquely  by  a  semi  tendinous  fascia  to  the  inner  edge 
of  the  ligamentum  patella,  and  to  the  inner  and  adjacent  border  of 
the  anterior  half  of  the  summit  of  the  tibia. 

Shape. — Large,  fleshy. 


112  ANATOMY   OF   THE   DOMESTIC   FOWL 

Relations. — Posteriorly,  with  the  gluteus  primus  and  the  vasti. 

Action. — Extends  the  leg,  flexes  and  adducts  the  thigh. 

Gluteus  Primus  (Fig.  23,  No.  8  and  9).  Location. — The  outer 
flat  massive  muscle  of  the  thigh. 

Origin. — By  a  thin  fascia  from  nearly  the  entire  length  of  the 
supero-internal  margin  of  the  pre-acetabular  portion  of  the  ilium, 
above  the  antitrochanter,  and  from  the  entire  length  of  the  post- 
acetabular  ridge. 

Insertion. — Near  the  patella  it  joins  the  tendon  of  the  extensor 
femoris,  and  by  aponeurosis  spreads  over  the  knee  and  is  inserted 
to  the  crest  of  the  upper  border  of  the  tibia,  the  patella  being 
incorporated  in  its  aponeurotic  ligament. 

Shape. — Triangular  in  shape,  it  is  aponeurotic  anteriorly  and  more 
fleshy  posteriorly. 

Relations. — Anteriorly,  covers  over  the  posterior  portion  of  the 
sartorius  and  the  body  of  the  gluteus  medius;  posteriorly,  bordered 
by  the  semitendinosus  and  the  biceps. 

Action. — Abducts  the  thigh. 

Gluteus  Medius  (Fig.  24,  No.  n).  Location. — Supero-anterior 
part  of  the  ilium  under  the  gluteus  primus. 

Origin. — From  the  entire  supero-internal  margin  of  the  pre-ace- 
tabular surface  of  the  ilium  and  the  concave  surface  on  the  adjacent 
bone. 

Insertion. — By  a  strong  tendon  which  passes  over  a  bursa  on  the 
anterior  rim  of  the  trochanter  and  is  inserted  obliquely  to  this 
trochanter. 

Shape. — A  fleshy  muscle  filling  the  concavity  of  the  pre-acetabular 
division  of  the  ilium. 

Relations. — Superiorly,  with  the  gluteus  primus;  inferiorly,  with 
the  gluteus  minimus. 

Action. — Abducts  and  pulls  the  femur  forward. 

Gluteus  Minimus  (Fig.  24,  No.  12).  (Synonym. — Gluteus 
profundus.) 

Location. — Beneath  the  medius  and  the  smaller  of  the  two. 

Origin. — To  the  anterior  margin  of  the  outer  border  of  the  ilium, 
and  from  the  siipero-external  surface  of  the  last  rib. 

Insertion. — The  fibers  extending  downward  and  backward  and 
outward  become  tendinous  and  are  inserted  below  the  trochanter 
of  the  outer  part  of  the  upper  third  of  the  femur. 

Shape. — Small,  fleshy. 


MYOLOGY  113 

Relations. — Inferiorly,  with  the  bone  and  superiorly,  with  the 
gluteus  medius. 

Action. — Abducts  and  pulls  the  thigh  forward. 

Extensor  Femoris  (Fig.  24,  No.  15).  Location. — Anterior  femoral 
region.  It  is  divided  into  two  parts:  the  vastus  externus  and  the 
crureus. 

Origin. — The  vastus  externus  (Fig.  24,  No.  14)  arises  tendinous 
from  the  base  of  the  trochanter  of  the  outer  part  of  the  femur  and 
from  this  point  down  the  bone  approximately  to  the  condyle. 
The  crureus  (Fig.  24,  No.  13)  originates  by  a  tendon  from 
the  anterior  upper  prominent  rim  of  the  trochanter,  from  this 
point  extending  down  the  ai  tero-external  part  of  the  shaft  of  the 
femur. 

Insertion. — Merges  with  the  gluteus  primus,  and,  by  a  fascia-like 
arrangement,  spreads  over  the  front  of  the  knee-joint  inserts  to  the 
patella  and  is  also  inserted  into  the  crest  of  the  tibia. 

Shape.- — Large,  fleshy. 

Relations. — Posteriorly,  with  the  femur  and  anteriorly,  with  the 
sartorius. 

Action. — Extends  strongly  the  leg  upon  the  thigh. 

Vastus  Interims  (Fig.  16,  No.  3).  Location. — Internal  and  lateral 
side  of  the  femur. 

Origin.  —  From  the  postero-internal  part  of  the  shaft  of  the  femur 
just  below  the  head,  and  in  a  straight  line  extending  down  the  femur. 

Insertion. — By  a  broad  tendon  along  the  thickened  inner  border 
of  the  summit  of  the  tibia. 

Shape.— Thick,  long. 

Relations. — Anteriorly,  with  the  bone;  surrounded  by  the  other 
crural  muscles. 

Action. — Extends  the  leg  upon  the  knee;  a  powerful  assistant  of 
the  extensor  femoris. 

Biceps  Flexor  Cruris  (Fig.  17,  No.  D,  i).  Location.  —Posterior 
tibial  region. 

Origin. — By  a  tendinous  fascia  from  the  post-acetabular  ridge, 
extending  between  the  antitrochanter  and  the  anterior  point  of  the 
insertion  of  the  semitendinosus. 

Insertion. — To  the  tuberosity  on  the  external  part  of  the  shaft  of 
the  fibula  a  short  distance  below  the  head. 

Shape. — Large,  rather  cone-shaped  with  base  directed  upward. 

Relations. — Anteriorly,  with  the  vastus  externus;  posteriorly,  with 


114  ANATOMY   OF   THE  DOMESTIC  FOWL 

the  semitendinosus.  The  inferior  tendinous  portion  passes  through 
a  tendinous  sling  or  pulley  called  the  biceps  band. 

Action. — Flexes  the  leg  upon  the  thigh. 

Semitendinosus  (Fig.  23,  No.  10).  Location. — Posterior  femoral 
region. 

Origin. — By  a  tough,  strong  fascia  from  the  surface  of  the  caudal 
muscles  and  from  the  posterior  third  of  the  post-acetabular  ridge. 

Insertion. — The  fibers  pass  downward  and  forward,  and  insert  to 
the  tendinous  raphe  along  the  posterior  margin  of  the  semitendinosus 
accessorius;  lower  down  it  merges  with  the  median  fascia  of  the 
inner  head  of  the  gastrocnemius. 

Shape. — Fleshy,  broad,  flat  and  long. 

Relations. — Internally,  with  the  semimembranosus  and  anteriorly, 
with  the  biceps  flexor  cruris. 

Action. — Flexes  the  leg. 

Semitendinosus  Accessorius.    Location. — Posterior  femoral  region. 

Origin. — From  an  oblique  line  just  above  the  condyle,  on  the 
posterior  of  the  shaft  of  the  femur. 

Insertion. — Its  fibers,  passing  upward  and  backward,  attach  them- 
selves to  the  tendinous  raphe  common  to  this  muscle  and  the  semi- 
tendinosus, and  are  finally  inserted  to  the  inner  side  of  the  shaft  of 
the  tibia. 

Shape. — Flat,  oblong. 

Relations. — Posteriorly  to  the  shaft  of  the  femur,  and  externally 
to  the  long  adductors  of  the  thigh. 

Action. — Aids  the  preceding  in  flexing  the  leg. 

Semimembranosus  (Fig.  24,  No.  17).  Location. — Postero-internal 
to  the  semitendinosus. 

Origin. — From  the  outer  surface  of  the  ischium,  beginning  at  the 
lower  margin  of  its  notch  on  the  posterior  pelvic  border,  extends  on 
a  curved  line  on  the  adjacent  surface  beyond. 

Insertion. — The  fibers,  passing  downward  and  forward,  insert  by  a 
broad,  thin  tendon  to  the  shaft  of  the  tibia  a  short  distance  below 
the  head  and  on  a  line  parallel  to  the  long  axis  of  the  tibia. 

Shape. — Long,  narrow,  ribbon-shaped. 

Relations. — Lies  adjacent  to  the  semitendinosus  and  in  the  same 
plane. 

Action. — Directly  flexes  the  leg. 

Femoro-caudal  (Fig.  24,  No.  8).  Location. — Infero-lateral  to 
the  caudal  and  post-femoral  region. 


MYOLOGY 


Origin. — By  a  delicate  tendon  from  the  base  of  the  pygostyle. 

Insertion. — By  a  thin,  flat  tendon  upon  the  outer  part  of  the  shaft 
of  the  femur  below  the  trochanter  and  at  about  the  juncture  of  the 
upper  and  middle  third  of  the  bone. 


FIG.  24. — Second  layer  of  muscles  of  the  thigh  of  a  cock.  Outside  view.  I, 
Appendico-costales.  2,  Levatores  costarum.  3,  Sacro-lumbalis.  4,  Longissi- 
mus  dorsi.  5,  Intercostales.  6.  Longissirnus  dorsi.  7,  Latissimus  dorsi.  8, 
Femoro-caudal.  9,  Edge  of  obturator  externus.  n,  Gluteus  medius.  12, 
Gluteus  minimus.  13,  Crureus.  14,  Vastus  externus.  15,  Extensor  femoris. 
16,  Biceps  flexor  cruris.  17,  Semimembranosus.  18,  Adductor  magnus.  19, 
Adductor  longus.  20  External  abdominal  oblique.  21,  Depressor  coccygi's. 
22,  Tibialis  anticus.  23,  Tibialis  posticus.  24,  Flexor  perforans  digitorum  pro- 
fundus.  25,  Flexor  perforatus  medius  secundus  pedis.  26,  Flexor  longus 
hallucis. 

Shape. — Long,  narrow,  spindle-shaped,  flattened  from  side  to  side. 

Relations. — Inferiorly  to  the  obturator  externus,  and  along  the 
upper  border  of  the  long  adductors  of  the  thigh  and  the  semi- 
membranosus. 

Action. — Pulls  the  tail  down  and  to  one  side. 


Il6  ANATOMY   OF   THE   DOMESTIC   FOWL 

Obturator  Externus  (Fig.  24,  No.  9) .  Location. — External  postero- 
lateral  side  of  the  pelvis. 

Origin. — From  the  posterior  half  of  the  periphery  of  the  ischiatic 
foramen  and  the  concavity  found  on  the  external  surface  of  the 
lateral  part  of  the  pelvis. 

Insertion. — The  fibers  pass  across  to  the  femur  and  are  inserted 
by  a  broad,  flat  tendon  to  the  shaft  of  the  femur  just  below  the 
trochanter. 

Shape— Thick,  fleshy. 

Relations. — Lies  just  above  the  femoro-caudal  muscle,  the  sciatic 
nerve  and  femoral  artery  pass  over  and  external  to  its  tendon. 

Action. — Pulls  the  head  of  the  femur  backward. 

Obturator  Interims  (Fig.  16,  No.  E,  i).  Location. — Occupies  the 
space  between  the  ischium  and  the  pubis. 

Origin. — From  the  ventral  surface  of  the  ischium,  including  the 
posterior  border,  from  the  inner  line  of  the  corresponding  post- 
pubis,  and  from  the  membrane  covering  the  space  between  these 
two  bones. 

Insertion. — Becoming  dense,  subcylindrical,  and  strong,  it  passes 
through  the  obturator  foramen  and  is  inserted  to  the  outer  part  of 
the  trochanter  of  the  femur,  in  common  with  the  gemellus  and 
opposite  to  the  insertion  of  the  gluteus  medius. 

Shape. — Subtriangular  and  flat  with  a  central  tendon;  bipenni- 
form. 

Relations. — Outside  the  pelvis  the  tendon  lies  upon  the  gemellus 
and  is  external  to  it.  Fills  the  obturator  foramen  and  the  space 
between  the  ischium  and  the  pubis. 

Action. — Acts  as  a  posterior  stay  to  the  head  of  the  femur. 

Gemellus  (Fig.  25,  No.  5).  Location. — Posterior  to  the  head  of 
the  femur. 

Origin. — From  the  fossa  between  the  acetabulum  and  the  obtura- 
tor foramen,  and  on  the  outer  side  of  the  pelvis. 

Insertion. — Its  fibers  are  attached  by  fascia  to  the  tendon  of  the 
obturator  internus,  and  pass  directly  to  the  trochanter  of  the  femur 
where  they  insert  in  common  with  that  of  the  obturator  internus. 

Shape. — Strong,  thick,  chunky. 

Relations. — Postero-external  to  the  head  of  the  femur. 

Action. — Like  the  two  preceding,  when  the  head  of  the  femur  is 
fixed,  it  pulls  the  pelvis  forward  and  steadies  it  on  the  head  of  the 
femur. 


MYOLOGY  117 

Adductor  Longus  (Fig.  24,  No.  19).  Location. — In  the  posterior 
femoral  region. 

Origin. — From  a  line  on  the  lateral  part  of  the  pelvis. 

Insertion. — The  fibers,  passing  downward  and  forward,  are~!ri~ 
serted  on  a  longitudinal  line  along  the  posterior  part  of  the  shaft  of 
the  femur. 

Shape.— Broad,  flat,  fleshy. 

Relations.  —Posteriorly  to  the  femur,  and  anteriorly  to  the  adduc- 
tor magnus. 

Action. — Adducts  the  thigh. 

Adductor  Magnus  (Fig.  24,  No.  18).  Location. — Posterior  femoral 
region. 

Origin. — From  the  line  constituting  the  lower  boundary  of  the 
ischiatic  fossa  on  the  outer  lateral  part  of  the  pelvis. 

Insertion. — The  fibers  pass  downward  and  are  inserted  to 
the  superior  curve  of  the  internal  femoral  condyle.  The  internal 
head  of  the  gastrocnemius  blends  with  this  muscle  just  above  its 
attachment. 

Shape. — Long,  narrow. 

Relations.- — Posteriorly  to  the  adductor  magnus  and  anteriorly 
to  the  semimembranosus. 

Action. — Strongly  adducts  the  thigh. 

THE  TIBIAL  GROUP 

Gastrocnemius  Tibialis  anticus 

Peroneus  longus  Extensor  hallucis  brevis 

Extensor  longus  digitorum  Flexor  perforatus  indicis 
Tibialis  posticus  secundiis  pedis 

Flexor  longus  hallucis  Flexor  perforatus  medius 
Flexor  perforatus  annularis  primus          primus  pedis 

pedis  Flexor  perforatus  indicis 
Flexor  perforatus  medius  secundus  primus  pedis 

pedis  Extensor  brevis  digitorum 

Flexor    perforans    digitorum   pro-  Flexor  hallucis  brevis 

fundus  Extensor   annularis  brevis 
Soleus 


Gastrocnemius    (Fig.    23,  No.   n).    Location. — Posterior   tibial 
region. 


Il8  ANATOMY   OF   THE   DOMESTIC   FOWL 

Origin. — There  are  three  heads:  the  internal,  the  external,  and 
the  tibial.  The  external  head  extends  by  a  short,  flattened,  strong 
tendon  from  the  postero-external  part  of  the  external  condyle  of 
the  femur;  the  internal  head  extends  from  the  outer  surface  of  the 
inner  condyle  of  the  femur;  and  the  tibial  head  extends  from  the 
entire  inner  rim  of  the  tibial  summit  and  from  the  free  edge  of  the 
adjacent  crest. 

Insertion. — At  the  lower  fourth  of  the  tibial  shaft,  terminates  in 
a  broad,  flat  tendon  which  passes  over  the  shallow,  longitudinal 
groove  of  the  tibial  cartilage,  and,  crossing  the  tibio-tarsal  joint, 
is  inserted  to  the  posterior  surface  of  the  hypotarsus  of  the  metatarsal 
bone,  and  finally,  below  this  point,  merges  into  the  podothecal 
sheath  confining  the  flexor  tendons. 

Shape. — Large,  fleshy,  somewhat  cone-shaped  with  the  base 
upward. 

Relations. — The  posterior  fleshy  muscle  of  the  post-tibial  region 
located  anterior  to  the  soleus. 

Action. — Extends  the  metatarsus  on  the  tibia. 

Soleus  (Fig.  25,  No.  G,  i).    Location. — The  posterior  tibial  region. 

Origin. — From  the  posterior  part  of  the  head  of  the  tibia. 

Insertion. — -By  a  long  slender  tendon  to  the  proximal  end  and 
toward  the  inner  angle  of  the  tibial  cartilage,  some  of  the  fibers 
passing  to  the  tendon  of  the  gastrocnemius. 

Shape.— Small,  flattened. 

Relations. — Anteriorly,  with  the  flexor  perforans  digitorum  pro- 
fundus  and  posteriorly,  with  the  gastrocnemius. 

Action. — Similar  to  that  of  the  gastrocnemius. 

Peroneus  Longus  (Fig.  23,  No.  12).  Location. — Antero-lateral 
tibial  region. 

Origin. — From  the  raised  crest  in  front  of  the  head  of  the  tibia, 
and  from  the  fascia  that  covers  the  outer  side  of  the  knee-joint. 

Insertion. — The  fibers,  passing  downward,  then  downward  and 
outward,  terminate  in  a  small  tendon  at  the  lower  third  of  the  tibia. 
This  tendon  bifurcates  just  above  the  tibial  condyles  at  the  outer 
part  of  the  limb,  the  shorter  and  stronger  attaches  to  the  fibrous 
fascia  covering  the  tibial  cartilage,  the  other  merging  with  the 
tendon  of  the  flexor  perforatus  medius  primus  pedis  about  i  cen- 
timeter below  the  hypotarsus  of  the  tarso-metatarsus. 

Relations. — Covers  over  all  the  muscles  of  the  anterior  tibial 
region. 


MYOLOGY  119 

Shape. — A  broad  muscular  sheet. 

Action. — Assists  the  flexor  perforatus  medius  primus  pedis. 

Tibialis  Anticus  (Fig.  24,  No.  22).  Location. — In  the  anterior 
tibial  region. 

Origin. — The  muscular  belly  may  be  easily  divided  into  two  parts. 
The  inner  head  extends  from  the  head  of  the  tibia  immediately 
beneath  the  peroneus  longus.  The  outer  head  arises  by  a  strong 
tendon  from  a  depression  on  the  antero-inferior  ridge  of  the  outer 
condyle  of  the  femur. 

Insertion. — The  tendon  passing  through  the  fibrous  ligamentous 
loop  just  above  the  tibial  condyles,  inserts  to  a  tubercle  on  the 
shaft  just  below  the  head  of  the  tarso-metatarsus. 

Shape. — Large,  fusiform. 

Relations.— Beneath  the  peroneus  longus. 

Action. — Flexes  the  metatarsus  upon  the  tibia. 

Extensor  Longus  Digitorum  (Fig.  25,  No.  G,  6).  Location. — An- 
terior tibial  region. 

Origin. — From  the  inferior  portion  of  the  crest  and  a  portion  of 
the  shaft  of  the  fibula. 

Insertion. — It  becomes  tendinous  at  the  lower  third  of  the  bone, 
passing  under  the  bony  ridge  just  above  the  condyle  in  front, 
and  over  the  ankle-joint.  It  is  bound  down  by  firm  fascia,  and  at 
the  trochlea  of  the  basal  toe  joints,  divides  into  three  small  tendin- 
ous slips.  These  pass  over  the  superior  part  of  the  second,  the 
third,  and  the  fourth  toes,  bifurcating  in  their  course,  and  are 
inserted  to  the  distal  ones. 

Shape. — Long,  penniform,  with  a  long,  slender  tendon. 

Relations. — Immediately  below  the  tibialis  anticus. 

Action. — Extends  the  digits  as  their  long  extensor. 

Extensor  Hallucis  Brevis  (Fig.  25,  No.  G,  4).  Location. — The 
anterior  metatarsal  region,  along-  the  antero-internal  edge. 

Origin. — From  just  below  the  summit  of  the  antero-internal  part 
of  the  head  of  the  tarso-metatarsus,  and  from  the  adjacent  shaft 
below,  and  from  the  tendon  of  the  tibialis  anticus. 

Insertion. — Into  the  process  at  the  superior  part  of  the  bone  of 
the  bony  claw  of  the  hallux. 

Shape. — Slender,  thin  in  diameter,  with  a  long,  slender  tendon. 

Relations. — Superiorly,  with  the  antero-internal  edge  of  the 
metatarsus  and  inferiorly,  its  tendon  with  the  top  of  the  hallux. 

Action. — Extends  the  hallux. 


120 


ANATOMY   OF   THE   DOMESTIC   FOWL 


Extensor  Brevis  Digitorum.     Location. — On  the  anterior  surface 
of  the  metatarsus. 


r 


FIG.  25. — Inner  layer  of  muscles  of  the  thigh  of   a  hen.     Outside  view. 

A.  Pad  of  fibrocartilage  or  meniscus  of  femoro-tibial  articulation,      i,  Inner 
semilunar  fibrocartilage.     2.  External  semilunar  cartilage.     3,  Anterior  border. 

B.  Tarsal  meniscus  or  pad  of  fibrocartilage. 

C.  Articular  surface  of  the  tarsal  joint,     i,  Posterior  ligamentum  cruciatum 
genu.     2,  Femoral  tendinous  insertion  of  tibialis  anticus.     3,  Ligamentum  tibio- 
fibulare.     4,    Ligamentum    interosseum.     5,   Ligamentum   transversum   of   the 
meniscus.     6,  Anterior  ligamentum  cruciatum  genu. 

D.  i,  Tibia.     2;  Fibula.     3,  Femur.     4,  External  ligamentum  laterale  genu. 

E.  Inferior  surface  of  the  tail  of  a  hen.     i,  Infracoccygis.     2,  Lateralis  coccy- 
gis. 

F.  Outside  pelvic  view.      I,  Obturator  ligament.     2,  Tendon  of  the  obturator 
internus.     3,  Ligamentum  oblongum.     4,  Ligamentum  capsulare.     5,  Gemellus. 

G.  Outside  view  of  leg  of  a  cock,     i,  Soleus.     2,  Flexor  longus  hallucis.     3, 
Flexor  perforans  digitorum  profundus.     4,  Extensor  brevis  hallucis.     5,  Extensor 
brevis   annularis.     6,    Extensor  longus   digitorum.     7,    Tendon   of   the   tibialis 
posticus. 

H.   i,  Transversalis  abdominalis.     2,  Cotyloid  cavity. 


Origin. — By  a  small  fleshy  belly  to  the  anterior  part  of  the 
proximal  end  of  the  metatarsus. 

Insertion. — It  becomes  tendinous  about  the  middle  third  of  the 
metatarsus.  Extending  down  the  anterior  face  of  the  metatarsus  it  is 


MYOLOGY  121 

inserted  to  the  inner  tubercle  of  the  base  of  the  first  phalanx  of 
the  outer  or  fourth  toe. 

Shape. — Long,  slender. 

Relations. — Posteriorly  with  the  metatarsus. 

Action. — Pulls  the  fourth  toe  upward  and  inward. 

Flexor  Hallucis  Brevis.  Location. — Postero-internal  side  of  the 
metatarsus. 

Origin. — Side  and  lower  margin  of  the  inner  aspect  of  the  hypo- 
tarsus  of  the  tarso-metatarsus  and  from  the  shaft  of  this  bone 
immediately  below  it. 

Insertion. — Winds  round  inner  side  of  basal  joint  of  the  hallux 
and  is  inserted  on  its  under  side. 

Shape.- — Small  flat  muscle  gradually  tapering  into  a  tendon. 

Relations. — Posteriorly  with  the  metatarsus. 

Action, — To  flex  the  hallux. 

Extensor  Annularis  Brevis.  Location. — On  postero-external  side 
of  metatarsus. 

Origin. — External  aspect  of  the  hypotarsus  and  the  shaft  below. 

Insertion. — Supero-external  part  of  the  basal  phalanx  of  the 
fourth  toe. 

Shape. — Small  flat  muscle. 

Relations. — Posteriorly  with  the  metatarsus. 

Action. — Extensor  of  the  fourth  toe. 

Tibialis  Posticus  (Fig.  24,  No.  23).  Location. — In  the  posterior 
tibial  region. 

Origin. — From  the  whole  shaft  of  the  fibula  below  the  insertion 
of  the  biceps  flexor  cruris,  and  from  the  shaft  of  the  tibia  a  short 
distance  below  this  insertion.  Also  from  the  interosseous  mem- 
brane, and  the  adjacent  surface  of  the  tibial  shaft. 

Insertion. — Passing  in  front  of  the  external  malleolus,  crossing  the 
ankle-joint,  finally  inserted  into  the  outer  edge  of  the  summit  of 
the  tarso-metatarsal  bone. 

Shape. — Long,  subcylindrical. 

Relations. — Medially,  with  the  flexor  perforans  digitorum  pedis; 
superiorly,  with  the  postero-external  portion  of  the  tibia. 

Action. — Extends  the  metatarsus  upon  the  tibia. 

Flexor  Perforatus  Indicis  Secundus  Pedis  (Fig.  17,  No.  5).  Loca- 
tion.— The  posterior  tibial  region. 

Origin. — From  the  external  surface  of  the  outer  condyle  of  the 
femur,  just  below  the  head  of  the  gastrocnemius. 


122  ANATOMY   OF   THE   DOMESTIC   FOWL 

Insertion. — Passing  in  an  oblique  manner  along  posterior  to  the 
tibia,  extends  through  the  superficial  part  of  the  tibial  cartilage  to 
the  outer  side  of  the  leg;  then  crossing  the  tibio-tarsal  joint,  it 
passes  through  a  special  canal  of  the  hypotarsus,  down  the  back 
of  the  tarso-metatarsus,  under  the  annular  ligament  of  the  sole  of 
the  foot  and  a  cartilaginous  structure  below  this  ligament,  over 
the  trochlea,  and  is  inserted  to  the  middle  shaft  of  the  second 
phalanx  of  the  second  toe. 

Shape. — Thin,  flat,  broadly  spindle-shaped. 

Relations. — Posteriorly,  with  the  flexor  perforatus  medius  secun- 
dus  pedis,  and  anteriorly,  with  the  flexor  perforatus  annularis 
primus  pedis. 

Action. — Flexes  the  toes. 

Flexor  Longus  Hallucis  (Fig.  17,  No.  7;  Fig.  25,  No.  2).  Loca- 
tion.— The  posterior  tibial  region. 

Origin. — By  two  tendinous  heads:  one  from  the  posterior  part  of 
the  femur,  just  below  the  two  condyles;  the  other  from  the  outer 
part  of  the  external  condyle  of  the  femur.  The  deep  flexor  passes 
between  these  two  heads. 

Insertion. — Becoming  tendinous  at  the  lower  third  of  the  leg, 
passes  beneath  the  superficial  flexors  in  a  special  canal  on  the  outer 
side  of  the  tibial  cartilage,  and  extends  through  the  large  canal  of 
the  hypotarsus  (Fig.  12,  No.  F,  5)  next  to  the  shaft,  then  down  to 
the  apex  of  the  accessory  metacarpal  bone.  It  is  inserted  to  the 
tubercle  on  the  inferior  proximal  end  of  the  ungual  phalanx. 

Shape. — Large,  fusiform. 

Relations. — With  the  exterior  of  the  deep  flexors. 

Action. — Flexes  the  hallux  as  its  long  flexor. 

Flexor  Perforatus  Annularis  Primus  Pedis  (Fig.  17,  Nos.  D,  8 
and  C,  6).  Location. — -The  posterior  tibial  region. 

Origin. — From  the  inner  side  of  the  belly  of  the  flexor  longus 
hallucis. 

Insertion. — Becoming  tendinous  at  the  lower  third  of  the  tibia, 
passes  a  little  to  the  outer  side  and  through  the  tibial  cartilage, 
then  over  the  ankle-joint  and  through  the  hypotarsal  canal  (Fig. 
12,  No.  5)  to  the  under  side  of  the  outer  toe,  where  it  forms  a  sheath 
through  which  the  deep  flexors  extend.  It  gives  off  on  either  side 
a  tendinous  slip  which  attaches  to  the  basal  phalanx. 

Shape. — Long,  slender,  compressed  laterally. 


MYOLOGY  I 23 

Relations.— Internally,  with  the  flexor  perforatus  indicis  secundus 
pedis,  and  externally,  with  the  flexor  longus  hallucis. 

Action. — Flexes  the  toes  as  their  long  flexor.  A  second  flexor  of 
the  outer  toe. 

Flexor  Perforatus  Medius  Secundus  Pedis  (Fig.  17,  No.  9). 
Location. — The  posterior  tibial  region. 

Origin. — From  a  strong  fascia  that  merges  with  the  knee-joint, 
and  by  a  tendon  from  the  external  condyle  of  the  femur  in  common 
with  the  tendon  of  the  flexor  perforatus  indicis  secundus  pedis. 

Insertion. — Continued  as  a  flattened  tendon  extending  from  the 
lower  third  of  the  leg,  passing  obliquely  through  the  tibial  cartilage 
and  then  through  the  interno-posterior  canal  of  the  hypotarsus, 
(Fig.  12,  No.  F,  5)  inserted  to  the  second  joint  of  the  middle  toe. 

Shape. — Long,  fusiform. 

Relations. — With  the  shaft  of  the  fibula,  which  it  covers. 

Action. — Flexes  the  middle  toe. 

Flexor  Perforatus  Medius  Primus  Pedis  (Fig.  17,  No.  2).  Loca- 
tion.— Posterior  tibial  region. 

Origin. — From  the  inner  side  of  the  muscular  portion  of  the  flexor 
perforatus  annularis  primus  pedis. 

Insertion. — Terminating  in  a  flattened  tendon,  passes  through 
the  tibial  cartilage  and  hypotarsus,  and  then  extends  along  the 
shaft  of  the  basal  joint  of  the  third  toe,  and,  dividing  into  two 
slips,  inserts  to  either  side  of  its  shaft. 

Shape. — Long,  rather  small. 

Relations. — With  the  flexor  perforatus  annularis  primus  pedis 
on  the  inner  side. 

Action. — Flexes  the  third  toe. 

Flexor  Perforatus  Indicis  Primus  Pedis  (Fig.  17,  No.  4).  Loca- 
tion.— The  posterior  tibial  region. 

Origin. — From  a  thin,  broad  tendon,  on  the  external  condyle  of 
the  femur,  in  common  with  the  flexor  perforatus  medius  secundus 
pedis. 

Insertion. — Becoming  tendinous,  passes  through  the  tibial  cartilage 
and  the  hypotarsus  of  the  metatarsus  (Fig.  16,  ^4)  and  inserts 
to  the  sides  of  the  basal  joint  of  the  second  toe. 

Shape. — Long,  slender,  fusiform;  somewhat  flattened  laterally. 

Relations. — With  the  flexor  perforatus  medius  secundis  pedis, 
posteriorly. 

Action. — A  flexor  of  the  toes. 


124  ANATOMY   OF   THE   DOMESTIC   FOWL 

Flexor  Perforans  Digitorum  Profundus  (Fig.  24,  No.  24  and 
Fig.  25,  No.  G,  3).  Location. — The  posterior  tibial  region. 

Origin. — From  the  posterior  part  of  the  external  condyle  of  the 
femur,  from  the  posterior  part  of  the  tibia  just  below  the  summit, 
and  from  a  point  near  the  origin  of  the  soleus. 

Insertion. — Its  heavy  flattened  tendon  passes  through  the  tibial 
cartilage,  this  tendon  dividing,  the  branches  pass  along  the  under 
side  of  the  toes,  perforating  the  outer  tendons  and  become  inserted 
to  the  proximal  tubercle  at  the  base  of  the  under  side  of  the  ungual 
phalanxes  of  the  second,  third,  and  fourth  toes. 

Shape. — Long,  fleshy,  with  a  long  tendon. 

Relations. — Closely  with  the  tibial  bone;  the  deepest  of  all  the 
flexors. 

Action. — Flexes  the  digits. 

THE  MUSCLES  OF  THE  EYE 

Orbicularis  palpebrarum  Levator  palpebrae  su- 

perioris 

Depressor  palpebrae  inferioris  Quadratus  nictitans 

Pyramidalis  nictitans  Obliquus  superior 

Obliquus  inferior  Rectus  superior 

Rectus  inferior  Rectus  externus 
Rectus  internus 


Orbicularis  Palpebrarum  (Fig.  7,  No.  30).  (Synonym. — Orbicu- 
laris oculi.) 

Location. — Upon  the  lacrimal  and  maxillary  bones. 

Origin. — From  the  lacrimal  and  maxillary  bones  and  the  ciliary 
margin. 

Insertion. — To  the  lower  free  edge  of  the  tarsal  cartilage. 

Shape. — Thin,  delicate  layer  of  fibers. 

Relations. — Externally,  with  the  skin;  internally,  with  the  lacri- 
mal and  the  maxillary  bones. 

Action. — Aids  in  closing  the  eye. 

Levator  Palpebrae  Superioris  (Fig.  7,  No.  24).  Location. — Along 
the  superior  roof  of  the  orbit. 

Origin.- — Along  a  longitudinal  line  found  near  the  middle  of  the 
roof  of  the  orbit. 


MYOLOGY  125 

Insertion. — To  the  ciliary  margin  of  the  upper  lid,  near  the  outer 
canthus. 

Shape. — Thin,  delicate  layer. 

Relations. — Superiorly,  with  the  bony  wall,  and  inferiorly,  with  the 
eyeball. 

Action. — Raises  the  superior  eyelid. 

Depressor  Palpebrse  Inferioris  (Fig.  7,  No.  29).  (Synonym. — 
Malaris.) 

Location. — Along  the  inferior  border  of  the  eye. 

Origin. — From  the  inferior  border  of  the  interorbital  foramen. 

Insertion. — To  the  lower  lid. 

Shape.— Thin,  flat,  delicate. 

Relations. — Superiorly,  with  the  eyeball;  inferiorly,  with  the 
inferior  orbital  wall. 

Action. — Pulls  the  lower  lid  down. 

Quadratus  Nictitans  (Fig.  26,  No.  B,  7).  Location. — Above  the 
eyeball  along  the  inferior  border  of  the  upper  wall  of  the  orbit. 

Origin. — From  the  sclerotic  from  the  upper  part  of  the  ball.  "   . 

Insertion. — To  the  upper  part  of  the  sheath  of  the  optic  nerve  near 
the  optic  foramen. 

Shape. — Broad,  thin,  quadrate. 

Relations. — Inferiorly,  with  the  eyeball;  superiorly,  with  the 
orbital  wall,  with  the  superior  oblique,  and  with  the  superior  rectus. 

Action. — Aids  in  pulling  the  nictitating  membrane  obliquely  out- 
ward and  downward  over  the  forepart  of  the  eyeball. 

Pyramidalis  Nictitans  (Fig.  26,  No.  B,  8).  Location. — Infero- 
posteriorly  to  the  eyeball. 

Origin. — From  the  lower  nasal  side  of  the  eyeball. 

Insertion. — The  fibers  converge  toward  the  upper  part  of  the 
optic  nerve,  into  a  tendon  which  passes  through  a  pulley  at  the 
free  margin  of  the  quadratus.  Inserts  to  the  lower  part  of  the 
margin  of  the  third  eyelid,  the  nictitans. 

Shape. — Pyramidal;  of  thin  layers  of  fibers. 

Relations. — Internally,  with  the  bony  orbital  wall;  externally, 
with  the  eyeball. 

Action. — Aids  the  quadratus  nictitans. 

Obliquus  Superior  (Fig.  26,  No.  B,  5).  (Synonym. — Obliquus 
dorsalis.) 

Location. — Superior  to  the  eyeball. 


126 


ANATOMY   OF   THE   DOMESTIC   FOWL 


FIG.  26. — Structures  of  the  eye  and  nasal  passage. 

A.  i,  The  anterior  turbinated  bone.     2,  The  posterior  turbinated  bones.     3, 
Orbital  gland.     4,  Ophthalmic  division  of  the  fifth  pair  of  cranial  nerves.     5, 
Section  through  the  cerebrum.     6,  Section  through  the  skull  showing  the  air 
spaces.     7,  Section  through  the  comb.     8,  Anterior  portion  of  the  upper  beak. 
9,  Edge  of  the  hard  palate. 

B.  The  intrinsic  muscles  of  the  eyeball,     i,    Superior  rectus. 
rectus.     3,   Inferior  rectus.     4,   External  rectus. 

ferior  oblique.     7,  Quadratus.     8,  Pyramidalis. 
membrana  nictitans. 

C.  Posterior  part  of  the  eye  showing  at  the  inferior  portion  of  the  ball  the 
pyramidalis  muscle  at  i,  and  at  2,  the  quadratus.     3,  Optic  nerve. 

D.  Inner  view  of  the  posterior  part  of  the  vitreous  chamber,     i, 
coat.     2,  Choroid  coat.     3,  Retina.     4,  Pecten. 

E.  Longitudinal  section  through  the  eye  of  a  hen.     i,  Cornea.     2, 
chamber.     3,  Scleral  ring.     4,  Crystalline  lense.     5,  Iris.     6,  Retina. 
otic.     8,  Choroid.     9,  Pecten.     10,  Optic  nerve,     n,  Vitreous  chamber. 

F.  An  edge  view  of  the  crystalline  lense  of  a  hen  showing  it  to  be  asymmetrical 
biconvex,     i,  The  anterior  side.     2,  The  posterior  side. 

G.  The  upper  section  through  the  anterior  portion  of  the  anterior  turbinated 
bone  showing  one  complete  circle  and  the  lower  a  section  through  the  middle 
turbinated  showing  one  and  one-half  turns. 


2,    Internal 
5,   Superior  oblique.     6,   In- 
9,  Optic  nerve.     10,  Edge  of 


Sclerotic 

Anterior 
7,  Scler- 


MYOLOGY  127 

Origin. — From  the  orbital  septum  just  back  of  the  inner  canthus, 
the  fibers  passing  backward  and  forward. 

Insertion. — Into  the  sclera,  anterior  to  the  sclerotic  plates. 

Shape. — Small,  thin,  fan-shaped. 

Relations. — With  the  eyeball,  superiorly;  at  its  extremities  with 
the  superior  rectus,  interiorly. 

Action. — Rotates  the  eyeball. 

Obliquus  Inferior  (Fig.  26,  No.  B,  6).  (Synonym. — Obliquus 
ventralis.) 

Location. — Inferior  to  the  eyeball. 

Origin. — From  the  interorbital  septum  near  the  inner  canthus 
of  the  eye. 

Insertion. — By  a  broad  expansion  to  the  inferior  portion  of  the 
eyeball. 

Shape. — Tendinous  at  its  insertions;  fan-shaped  as  it  passes  down- 
ward and  outward. 

Relations. — Internally,  with  the  eyeball;  and  externally,  with  the 
bony  orbital  wall,  with  the  inferior  rectus  muscle,  inferiorly. 

Action. — Aids  in  rotating  the  eye;  opposes  the  obliquus  superior. 

Rectus  Superior  (Fig.  26,  No.  B,  i).     (Synonym. — Rectus  dorsalis.) 

Location. — Superior  to  the  eyeball. 

Origin. — Along  the  supero-posterior  border  of  the  optic  foramen. 

Insertion. — To  the  sclera  just  within  the  margin  of  the  bony  circle 
of  the  eye. 

Shape. — Flat,  thin. 

Relations. — Internally,  with  the  obliquus  superior;  superiorly, 
with  the  bony  wall  of  the  orbit. 

Action. — To  pull  the  eyeball  upward. 

Rectus  Inferior  (Fig.  26,  No.  -6,3).     (Synonym. — Rectus  ventralis.) 

Location. — Inferior  to  the  eyeball. 

Origin. — From  the  inferior  border  of  the  optic  foramen. 

Insertion. — To  the  lower  portion  of  the  eyeball  within  the  margin 
of  the  bony  circle  of  the  eye. 

Shape. — Thin,  fan-shaped. 

Relations.- — Superiorly,  with  the  eyeball;  inferiorly,  with  the 
bony  wall  of  the  orbit. 

Action. — Pulls  the  eyeball  downward. 

Rectus  Externus  (Fig.  26,  No.  B,  4).  (Synonym. — Rectus 
lateralis.) 

Location. — External  to  the  eyeball. 


128  ANATOMY   OF   THE   DOMESTIC   FOWL 

Origin. — By  two  heads  infero-laterally  to  the  optic  foramen. 

Insertion. — To  the  postero-external  side  of  the  eyeball. 

Shape. — Short,  fan-shaped. 

Relations. — Internally,  with  the  eyeball;  externally,  with  the  bony 
wall  of  the  orbit. 

Action. — Pulls  the  eyeball  outward. 

Rectus  Interims  (Fig.  26,  No.  B,  2).  (Synonym. — Rectus 
medialis.) 

Location. — Inner  side  of  the  eyeball. 

Origin. — From  the  supero-anterior  border  of  the  optic  foramen. 

Insertion. — To  the  sclera  on  the  anterior  portion  of  the  eyeball. 

Shape. — Thin,  fan-shaped. 

Relations. — Internally,  with  the  eyeball  and  with  the  pyramidalis; 
externally,  with  the  bony  wall  of  the  orbit. 

Action. — Pulls  the  eyeball  inward. 

THE  MUSCLES  OF  THE  EAR 

Circumconcha  Tensor  tympani 


Circumconcha  (Fig.  7,  No.  32).  Location. — Surrounds  the  exter- 
nal ear. 

Origin  and  Insertion. — The  Circumconcha,  surrounding  the  periph- 
ery of  the  ear,  is  adherent  to  the  skull  and  loosely  to  the  skin,  and 
is  attached  to  the  outer  terminus  of  the  supra-occipital  crest. 

Relations. — Internally,  with  the  skull;  externally,  with  the  skin. 

Action. — Relaxes  the  tympanum. 

Tensor  Tympani  (Fig.  7,  No.  31).  Location. — External  to  the 
quadrate  and  to  the  external  auditory  meatus. 

Origin  and  Insertion. — From  the  surface  of  the  quadrate  and  the 
inner  end  of  the  quadra  to- jugal  to  the  inner  surface  of  the  tympanum. 

Shape. — A  few  fibers. 

Relations. — Internally,  with  the  quadrate  and  the  quadra  to- jugal; 
externally,  the  integumental  duplicature. 

Action. — Tenses  the  tympanum. 

FUNCTIONS  OF  MUSCLES 

To  cause  the  feathers  on  the  top  of  the  head  to  lie  flat: 

Dermo-frontalis. 

To  raise  the  feathers  along  the  superior  part  of  the  neck  and  along  the  dorsal 
region: 

Dermo-dorsalis. 


MYOLOGY  129 

To  tense  the  patagial  region : 

Dermo-tensor  patagii, 

Dermo-temporalis. 
To  cause  the  feathers  to  lie  close  to  the  body: 

Dermo-humeralis, 

D  ermo-pec  to  ralis . 
To  tense  the  lateral  cervical  integument: 

Dermo-temporalis. 
To  support  the  lingual  apparatus  and  superior  larynx: 

Platysma  myoides. 
To  manipulate  the  feathers  and  skin  of  the  inferior  part  of  the  neck : 

Cleido-trachealis. 
To  control  the  skin  in  the  shoulder  region: 

Dermo-spinalis. 
To  cause  the  feathers  of  the  back  to  lie  close  to  the  skin: 

Dermo-iliacus. 
To  depress  the  humeral  region: 

Dermo-ulnaris. 
To  close  the  jaw: 

Temporalis, 

Pterygoideus  internus, 

Pterygoideus  externus, 

Masseter. 
To  open  the  jaw: 

Biventer  maxilla, 

Entotympanic. 
To  raise  the  trachea  and  hyoid  apparatus: 

Digastricus. 
To  elevate  the  tongue: 

Mylo-hyoideus. 
To  pull  the  tongue  to  one  side: 

Singly1— 

Cerato-hyoideus, 
Stylo-hyoideus. 

Alone  when  the  larynx  is  fixed — 

Sterno-hyoideus . 
Those  which  protrude  the  tongue  from  the  mouth: 

Together— 

Cerato-hyoideus 
Genio-hyoideus. 
To  aid  in  deglutition: 

When  the  base  of  the  tongue  is  fixed — 

Sterno-hyoideus. 
To  depress  the  tongue: 

Together— 

Sterno-hyoideus . 

1  Muscles  are  arranged  in  pairs.     Singly  means  one  muscle  acting  alone,  i.e., 
without  its  fellow;  together  means  acting  both  at  the  same  time. 
9 


130  ANATOMY    OF   THE   DOMESTIC   FOWL 

To  depress  the  tip  of  the  tongue  and  elevate  the  base: 

Depressor  glottis. 
To  elevate  the  hyoid  arches : 

Cerato-glossus. 
To  extend  the  head : 
Complexus, 

Rectus  capitis  anticus  minor. 
To  flex  the  head  upon  the  neck: 

Flexor  capitis  inferior. 
To  extend  the  head  on  the  neck  and  elevate  the  neck . 

Biventer  cervicis. 
To  raise  the  neck  upward: 
Longus  colli  posticus. 

To  flex  each  vertebra  on  the  preceding  or  succeeding  laterally: 
Obliquus  colli, 
Intertransversales. 
To  pull  the  neck  downward: 

Longus  colli  anterior. 
To  pull  the  head  downward : 
Together— 

Rectus  capitis  lateralis, 
Trachelo-mastoideus . 

To  pull  the  head  downward  and  to  one  side: 
Singly— 

Rectus  capitis  lateralis, 
Trachelo-mastoideus . 
To  approximate  the  spinous  processes  of  the  vertebrae . 

Interspinales. 
To  approximate  the  vertebrae  in  a  supero-lateral  direction : 

Interarticulares. 
To  flex  the  vertebrae  supero-laterally : 

Obliquo-transversales. 
To  extend  the  neck: 

Together  when  the  first  rib  is  fixed — 

Scalenus  medius. 
To  close  the  glottis: 

Constrictor  glottidis. 
To  open  the  glottis: 

Thy  reo-ary  tenoideus . 
To  approximate  the  trachea!  rings: 

Tracheo-lateralis. 
To  tense  the  inferior  larynx: 
Broncho-trachealis  posticus, 
Broncho-trachealis  anticus 
Broncho-trachealis  brevis, 
Bronchialis  posticus, 
Bronchialis  anticus. 


MYOLOGY  131 


To  relax  the  inferior  larynx: 

Sterno-trachealis. 
To  aid  in  respiration: 

When  the  first  rib  is  fixed — 

Intercostales. 
When  wing  is  fixed — 
Latissimus  dorsi, 
Dermo-cleido  dorsalis. 
When  the  scapula  is  fixed — 
Serratus  magnus  anticus, 
Serratus  parvus  anticus, 
Thoraco-scapularis, 
Levatores  costarum, 
Appendico-costales, 
Triangularis  sterni. 
To  flex  the  shoulder-joint: 

Latissimus  dorsi. 
•To  elevate  the  humerus: 

Latissimus  dorsi. 
To  draw  the  scapula  forward: 
Trapezius, 
Rhomboideus. 
To  close  the  wing: 

Teres  et  infraspinatus. 
To  extend  the  humerus : 
Coraco-humeralis, 
Scapulo-humeralis. 

To  pull  the  humerus  upward  and  backward 
When  the  scapula  is  fixed — 

Supraspinatus. 
To  pull  the  coracoid  outward  :"! 

Subclavius. 
To  depress  the  wing: 

Coraco-brachialis. 
To  depress  the  scapula: 

When  the  ribs  are  fixed — 

Thoraco-scapularis. 
To  rotate  the  humerus: 

Subscapularis. 
To  flex  the  forearm: 
Pronator  brevis, 
Biceps, 

Brachialis  anticus,     * 
Anconeus, 

Tensor  patagii  longus, 
Tensor  patagii  brevis. 
To  extend  the  arm: 
Deltoid. 


132  ANATOMY   OF   THE   DOMESTIC   FOWL 

To  extend  the  antibrachial  region: 

Triceps. 
To  raise  and  to  draw  the  hand  forward: 

Extensor  metacarpi  radialis  longior. 
To  extend  the  digit: 

Extensor  indicis  longus, 

Extensor  digitorum  communis, 

Extensor  proprius  pollicis, 

Interosseous  dorsalis. 
To  supinate  the  radial  region : 

Supinator  brevis. 
To  flex  the  hand: 

Flexor  metacarpi  radialis. 
To  pronate  the  forearm: 

Pronator  brevis, 

Pronator  longus. 
To  extend  the  hand  on  the  forearm: 

Extensor  ossis  metacarpi  pollicis. 
To  flex  the  digit: 

Flexor  minimi  digiti, 

Flexor  digitorum  sublimis, 

Flexor  brevis  pollicis, 

Flexor  digitorum  profundus, 

Interosseous  palmaris. 
To  flex  the  hand  upon  the  forearm : 

Flexor  carpi  ulnaris, 

Flexor  carpi  ulnaris  brevior. 
To  rotate  the  hand  toward  the  body : 

Flexor  carpi  ulnaris  brevior. 
To  abduct  the  digits: 

Abductor  minimi  digiti. 
To  flex  the  metacarpus: 

Flexor  metacarpi  brevis. 
To  extend  the  leg: 

Sartorius. 
To  adduct  the  thigh: 

Sartorius, 

Adductor  longus, 

Adductor  magnus. 
To  abduct  the  thigh: 

Gluteus  primus, 

Gluteus  medius, 

Gluteus  minimus. 
To  pull  the  thigh  forward : 

Gluteus  minimus, 

Gluteus  medius. 
To  extend  the  leg  upon  the  thigh: 

Extensor  femoris, 


MYOLOGY  133 

Vastus  internus. 
To  extend  the  leg  upon  the  knee : 

Vastus  internus. 
To  flex  the  leg  upon  the  thigh : 

Biceps  flexor  cruris, 

Semitendinosus, 

Semitendinosus  accessorius, 

Semimembranosus. 
To  pull  the  tail  down  and  to  one  side: 

Femoro-caudal. 
To  pull  the  head  of  the  femur  backward: 

Obturator  externus. 
To  act  as  a  posterior  stay  to  the  head  of  the  femur: 

Obturator  internus. 
To  pull  the  pelvis  forward  and  to  steady  it  on  the  head  of  the  femur: 

Gemellus, 

Obturator  internus, 

Obturator  externus. 
To  extend  the  metatarsus  on  the  tibia: 

Gastrocnemius, 

Soleus, 

Tibialis  posticus. 
To  flex  the  toes: 

Peroneus  longus, 

Flexor  perforatus  medius  primus  pedis, 

Flexor  perforatus  indicis  secundus  pedis, 

Flexor  perforatus  medius  secundus  pedis, 

Flexor  perforatus  indicis  primus  pedis, 

Flexor  perforans  digitorum  profundus, 

Flexor  longus  hallucis, 

Flexor  perforatus  annularis  primus  pedis. 
To  flex  the  metatarsus  on  the  tibia : 

Tibialis  anticus. 
To  extend  the  toes: 

Extensor  longus  digitorum, 

Extensor  hallucis  brevis. 
To  flex  the  back  laterally  and  to  aid  in  raising  the  body. 

Sacro-lumbalis, 

Longissimus  dorsi. 
To  elevate  the  tail: 

Levator  coccygis, 

Levator  caudae. 
To  depress  the  tail: 

Depressor  caudae, 

Infracoccygis. 

Together- 
Depressor  coccygis, 
Lateralis  caudae. 


134  ANATOMY   OF   THE  DOMESTIC  FOWL 

To  pull  the  tail  downward  and  to  one  side: 

Singly — 

Lateralis  coccygis. 

Depressor  coccygis, 
Lateralis  caudae. 
To  close  the  eyelids: 

Orbicularis  palpebrarum. 
To  raise  the  superior  eyelid: 

Levator  palpebrae  superioris : 
To  pull  the  lower  eyelid  downward: 

Depressor  palpebrae  inferioris. 
To  pull  the  membrana  nictitans  over  the  eyeball: 

Quadratus  nictitans, 

Pyramidalis  nictitans. 
To  rotate  the  eyeball: 

Obliquus  superior, 

Obliquus  inferior. 
To  pull  the  eyeball  upward: 

Rectus  superior. 
To  pull  the  eyeball  downward: 

Rectus  inferior. 
To  pull  the  eyeball  outward: 

Rectus  externus. 
To  pull  the  eyeball  inward: 

Rectus  internus. 
To  tense  the  ear  drum: 

Tensor  tympani. 
To  relax  the  ear  drum: 

Circumconcha. 
To  depress  the  humerus: 

Pectoralis  major. 
To  raise  the  humerus: 

Pectoralis  secundus, 

Pectoralis  tertius. 


SPLANCHNOLOGY 

The  Digestive  Apparatus.— This  apparatus,  apparatus  digestorius, 
consists  of  the  organs  directly  concerned  in  the  reception  of  food,  in 
its  passage  through  the  body,  and  in  the  expulsion  of  the  unabsorbed 
portion.  For  convenience,  these  organs  are  grouped  as  follows:  the 
alimentary  canal  and  the  accessory  organs. 

The  alimentary  canal  is  a  tube  which  extends  from  the  mouth  to 
the  anus.  It  has  a  complete  lining  of  mucous  membrane,  external 
to  which  is  an  almost  continuous  muscular  coat.  The  abdominal 
portion  of  the  tube  is  largely  covered  with  a  serous  membrane,  the 
visceral  peritoneum.  The  canal  consists  of  the  following  consecutive 
segments:  mouth,  pharynx,  first  portion  of  the  esophagus,  crop, 
second  portion  of  the  esophagus,  proventriculus,  gizzard,  small 
intestine,  large  intestine,  and  cloaca. 

The  accessory  organs  are  beak,  tongue,  salivary  glands,  liver,  and 
pancreas. 

The  Mouth  (Fig.  27). — The  distinctive  character  of  the  mouth 
of  the  fowl  consists,  in  the  absence  of  lips  and  teeth  and  instead  of 
jaw  bones  of  other  animals,  of  a  beak.  The  edge  of  the  beak  is 
covered  by  a  horn-like  gum.  The  shape  of  the  beak  differs  in  the 
various  classes  of  birds.  In  the  chicken  the  beak  is  short,  strong, 
thick,  and  pointed;  in  palmipeds  it  is  flattened.  The  upper  mandi- 
ble extends  out  over  the  lower  mandible.  The  outer  portion  of  the 
upper  and  the  lower  beaks  is  covered  by  a  horny  sheath.  There 
is  no  velum,  and  the  mouth  cavity  is  extended  rather  continuously 
into  the  pharynx  (Fig.  27,  No.  4).  The  posterior  cross  bar  of  the 
hard  palate  (Fig.  27,  No.  5),  which  possesses  a  row  of  filiform  papillae 
projecting  backward,  marks  the  upper  boundary  line  of  the  mouth; 
while  the  posterior  end  of  the  tongue  (Fig.  27,  No.  6),  likewise  with 
a  row  of  filiform  papillae,  marks  its  lower  boundary  line. 

Paris  of  the  Mouth. — The  mouth  of  fowls  is  divided  into  an  upper 
and  a  lower  half.  The  upper  half  is  divided  into  an  anterior  and  a 
posterior  part. 

The  anterior  part  extends  from  the  anterior  tip  of  the  beak  to  the 
posterior  nares.  It  is  further  divided  into  an  outer  hard  part  and 

135 


136  ANATOMY   OF   THE   DOMESTIC   FOWL 

an  inner  soft  part.  .The  outer  part  is  covered  by  epithelium  which 
may  be  considered  as  a  continuation  from  the  upper  outer  portion 
of  the  beak.  A  portion  of  this  is  cornified.  The  inner  part  is  cov- 
ered by  a  mucous  membrane  containing  mucous  glands,  nerves,  and 
blood-vessels. 

In  the  posterior  part  of  the  upper  half  of  the  mouth,  are  situated 
the  posterior  nares  (Fig.  27,  No.  10)  which  appear  as  a  longitudinal 


FIG.  27. — Mouth  and  pharynx  of  a  cock  laid  open,  i,  Eye.  2,  Edge  of  beak 
covered  with  a  horn-like  gum.  3,  Tongue.  4,  Pharynx.  5,  Posterior  cross  bar 
of  hard  palate.  6,  Posterior  end  of  tongue.  7,  Anterior  end  of  esophagus. 
8,  Phrenum.  9,  Palatal  papillaries.  10,  Posterior  nares. 


slit  in  the  center  of  the  hard  palate.  There  is  also  found  in  this 
part  a  furrow  which  contains  the  opening  of  the  Eustachian  tubes, 
or  tubae  auditivae.  There  are  also  two  ridges  near  the  same  pos- 
terior part  in  which  are  red  and  white  papillae,  which  may  appear 
in  rows,  and  which  contain  mucous  glands. 

The  lower  half  of  the  mouth  lies  between  the  lower  jaw  bones  and 
the  walls  of  the  mouth  cavity.     The  tongue  is  attached  here  by 


SPLANCHNOLOGY 


137 


means  of  the  phrenum  (Fig.  27,  No.  8).     This  half  of  the  mouth 
forms  a  pocket-like  structure  which  aids  in  taking  up  the  food. 

The  mouth  cavity  is  lined  with  stratified  squamous  epithelium, 
continuous  with  that  of  the  pharynx  and  the  esophagus.  Taste 
buds  are  located  in  the  mucous  membrane  of  the  mouth. 


FIG.  28. — Various  anatomical  parts  of  the  fowl. 

C.  A  section  through  the  nasal  region  of  the  fowl,     i,  Nasal  passages  showing 
the  turbinated  bones  dividing  the  nasal  passage  into  the  superior,  middle  and 
inferior  meati.     2,  The  infra-orbital  sinus.     3,  The  hard  palate. 

D.  Herbst's  touch  corpuscle  from  the  beak  of  a  quail. 

E.  A  vertical  section  through  the  ductus  cochlearis  of  a  pigeon,     i,  A  blood- 
vessel.    2,  The  periosteum.     3,  The  bony  structure.     4,  The  vascular  integu- 
ment.    5,  The  scala  vestibuli.     6,  The  inner  hyaline  cylindrical  cells.     7,  The 
membrana  tectoria.     8,  The  papilla  acustica  basilaris.     9,  The  membrana  basila- 
ris.     10,  The   scala  tympani.     n,  The   ganglion  of  the  cochlear  nerve  in  the 
ramus  basilaris.     12,  The  periosteum  (Gadow). 

F.  A  corpuscle  of  the  soft  papilla  of  a  duck's  tongue. 

J.  A  transverse  section  through  a  feather  papilla,  i,  The  pulp.  2,  The  mal- 
pighian  layer.  3,  The  corium.  4,  The  stratum  corneum  of  the  papilla.  5,  The 
malpighian  cell  group  of  the  main  shaft.'  6,  The  horny  sheath. 

In  many  water  fowls,  as  geese  and  ducks,  the  gum  edge  of  the 
mandible  has  grooves  extending  crosswise,  in  which  are  numerous 
terminals  of  the  trigeminus  nerve  arranged  as  taste  organs  (Fig.  29, 
G  and  Fig.  28,  D  and  F).  In  many  birds  of  prey  and  in  water  birds, 
e.g.,  the  goose  and  the  duck,  there  is  found  at  the  base  of  the  beak, 
a  very  thin,  nervous  or  sensitive  skin,  waxy  in  appearance,  called 
the  ceroma. 


ANATOMY   OF   THE  DOMESTIC   FOWL 

2 


FIG.  29. — Various  anatomical  parts  of  the  fowl. 

A.  i,    The   superior  semicircular  canal.     2,    The  vestibular  nerve.     3,   The 
meatus  auditorius  internus — the  entrance  of  the  auditory  nerve.     4,  The  entrance 
of  the  cochlear  nerve.     5,  Posterior  semicircular  canal.     6,  The  ampulla. 

B.  Side  papilla  of  the  tongue.      I  and  2,  Papillae  showing  a  fibrous  central  core 
supporting  blood-vessels  and  nerves.     3,  The  basement  membrane  consisting  of 
connective  tissue. 

G.  Herbst's  corpuscle  of  the  tongue  of  a  duck,  showing  the  capsule,  lamella 
and  around  the  nerve  zone,  numerous  round  bodies  arranged  in  two  rows. 


SP  LANCHNOLOGY 


The  Hard  Palate. — The  hard  palate,  palatum  durum,  forming  the 
roof  of  the  mouth  has  for  its  boundaries  the  beak  anteriorly,  the 
mandibular  arches  laterally,  and  the  pharynx  posteriorly.  It  has 
four  or  five  transverse  bars,  projecting  posteriorly  from  eacli  of 
which  is  a  row  of  filiform  papillae  (Figs.  27  and  29). 


FIG.  30. — A  section  through  the  wall  of  the  crop  of  a  hen.  i,  The  outer 
muscular  layer  showing  longitudinal  fibers.  2,  The  inner  muscular  layer  showing 
the  sectioned  ends  of  the  bundles  of  muscle  fibers.  3,  Stratified  squamous  epi- 
thelium. 4,  The  outer  surface  or  lumen  of  a  fold.  5,  The  stroma,  muscularis 
mucosa,  and  submucosa. 

The  beak  (Fig.  4,  No.  i)  with  little  if  any  aid  from  the  tongue, 
is  the  prehensile  organ. 

The  Tongue  (Fig.  27,  No.  3).  Location. — The  tongue  (lingua)  of 
the  fowl  is  situated  in  the  floor  of  the  mouth  between  the  rami  of  the 

H.  From  the  cristae  acoustica  of  the  ampulla  of  the  dove.  A,  A  vertical  section 
with  isolated  fiber  cells,  i  and  2,  The  nerve  fibers.  3,  The  hair  cells. 

/.  A  longitudinal  section  through  a  feather  papilla  showing  a  young  feather. 
i,  The  developing  feather.  2,  The  horny  sheath:  3,  The  epithelium.  4, 
Stratum  corneum.  5,  Stratum  malpighi.  6,  Corium.  7,  Malpighian  cell 
group  of  the  follicle. 


140 


ANATOMY    OF    THE   DOMESTIC   FOWL 


lower  mandible,  and  is  slung  to  the  cranium  by  the  cerato-branchial 
element  of  the  os  hyoideum  (Fig.  18,  No.  2). 

Shape. — The  tongue,  is  pointed  in  front  and  wide  behind,  shaped 
like  an  Indian  arrow-head,  and  is  supported  by  the  bony  and 
cartilaginous  hyoid  apparatus  (Fig.  9,  A). 


FIG.  31. — The  visceral  organs  of  the  hen.  i,  Tongue.  2,  Larynx.  3,  Glottis. 
4,  First  portion  of  the  esophagus.  5,  Crop.  6,  Second  portion  of  the  esophagus. 
7,  Proventriculus.  8,  Duodenum.  9,  Free  or  floating  portion  of  the  small  intes- 
tine. 10,  Mesentery  supporting  the  free  portion  of  the  small  intestine,  n, 
Caeca.  12,  Rectum  or  large  intestine.  13,  Cloaca.  14,  Anus.  15,  Liver. 
16,  Gall-bladder.  17,  Pancreas.  18,  Gizzard.  19,  Trachea.  20,  Lungs. 
21,  Spleen. 

Structure. — The  free  part  of  the  tongue  consists  of  two  long  tubes 
which  are  formed  by  the  rolling  in  of  the  ventral  sides  of  its  horny 
coverings.  The  dorsal  plate,  which  constitutes  one-half  of  the 


SPLANCHNOLOGY  141 

horny  sheath,  does  not  form  a  part  of  the  tubes,  but  ends  in  the 
region  of  the  point  of  the  entoglossum. 

The  top  surface  is  covered  by  a  thick  stratum  corneum,  giving  it 
a  rather  horny  surface.     Glands  occur  in  the  posterior  part  of  the- 
tongue. 

While  not  so  freely  movable  as  in  mammals,  the  tongues  of  birds 
are  very  flexible. 

The  Pharynx  (Fig.  27).  Location. — The  anterior  part  of  the 
pharynx  joins  with  the  mouth  and  the  posterior  part  with  the  upper 
portion  of  the  esophagus  and  the  superior  larynx.  The  pharynx  is 
bounded  anteriorly  by  the  base  of  the  tongue  and  by  the  posterior 
edge  of  the  hard  palate.  Posteriorly,  it  is  marked  by  the  entrance  of 
the  esophagus  and  by  a  ridge  of  filiform  papillae  located  on  the 
supero-posterior  part  of  the  larynx,  called  the  palatal  papillaries. 
A  few  filiform  papillae  stud  the  roof.  The  pharynx  communicates 
anteriorly  with  the  posterior  nares  and  the  mouth,  and,  posteriorly, 
with  the  esophagus  and  the  larynx. 

Shape. — The  pharynx  is  a  musculo-membranous  sac. 

Structure. — The  pharynx  is  lined  with  a  mucous  membrane 
covered  by  squamous  epithelium.  The  mucous  membrane  is  thrown 
into  irregular  folds.  The  bird  has  two  Eustachian  tubes.  Pneu- 
matic apertures  conduct  the  air  from  the  Eustachian  tubes  to  the 
pericranial  diploe. 

In  the  posterior  pharyngeal  roof  is  situated  the  infundibular 
crevice. 

Function. — The  function  of  the  pharynx  is  to  give  passage  for  the 
air  from  the  posterior  nares  to  the  larynx,  and  to  give  passage  for 
the  food  from  the  mouth  to  the  esophagus. 

Glands  Adjacent  to  the  Mouth  and  to  the  Pharynx. — The 
mucous  membrane  adjacent  to  the  glottis  and  in  the  roof  of 
the  mouth  contains  alveolar  glands.  The  angular  gland  of  the 
mouth,  located  beneath  the  zygomatic  arch,  by  some  anatomists  is 
considered  the  rudimentary  parotid  gland.  The  sublingual  glands, 
or  glandulae  sublinguales,  are  well  developed  (Fig.  17,  No.  B,  4). 
They  form  conical  masses,  with  the  apex  directed  anteriorly,  and 
occupy  a  portion  of  the  intermaxillary  space.  Several  ducts  from 
these  glands  open  into  the  mouth  cavity.  In  the  palatine  region 
there  are  also  located  glands  called  the  palatine  glands,  which  open 
by  many  stomata  upon  the  surface. 


142  ANATOMY   OF   THE   DOMESTIC   FOWL 

The  Esophagus  (Fig.  18,  No.  6).  Location  and  Shape. — The 
esophagus  is  a  musculo-membranous  tube,  capable  of  great  dis- 
tension, which  extends  from  the  pharynx  to  the  proventriculus. 
(Fig.  35,  No.  i,  and  3). 

The  esophagus  communicates  anteriorly  with  the  pharynx.  It 
extends  down  the  neck,  lying  supero-laterally  with  regard  to  the 
trachea  and  toward  the  right  side.  It  enters  the  thorax  above  the 
trachea,  and,  passing  through  between  the  bronchi,  terminates  into 
the  proventriculus.  At  the  entrance  of  the  thorax  and  just  to  the 
right  of  the  median  line,  it  expands  into  the  crop  which  divides  it 
into  two  portions,  designated  as  the  first  and  the  second.  The 
first  portion  of  the  esophagus  is  the  longer,  the  length  depending 
upon  the  size  and  kind  of  fowl. 

Structure. — The  wall  is  composed  of  four  coats,  the  mucous 
membrane,  the  submucosa,  the  muscular  coats,  and  the  fibrous 
sheath  or  tunic.  The  mucous  membrane  is  pale  and  is  covered  with 
stratified  squamous  epithelium. 

The  mucous  membrane  is  loosely  attached  to  the  muscular  coat 
by  the  submucosa.  Except  during  deglutition  it  lies  in  longitudinal 
folds  which  obliterate  the  lumen.  Opening  from  the  mucosa  are 
lenticular  glands,  which  may  be  seen  on  inflating  an  esophagus 
and  looking  through  its  transparent  walls. 

The  muscular  coat  of  the  esophagus  is  divided  into  two  layers, 
an  outer  longitudinal  and  an  inner  circular  layer. 

The  outer  fibrous  sheath  connects  the  esophagus  loosely  to  the 
surrounding  structures. 

Function. — The  function  of  the  esophagus  is  to  give  passage  way 
for  the  food  from  the  pharynx  to  the  crop  and  from  the  crop  to  the 
proventriculus. 

The  Crop  (Fig.  35,  No.  2 ;  Figs.  30  and  31).  Location  and  Shape. — 
The  crop,  or  ingluvies,  saccular  in  shape,  is  located  at  the  entrance 
of  the  thorax  and  just  to  the  right  of  the  median  line.  The  first 
portion  of  the  esophagus  empties  into  the  crop  superiorly  and 
inferiorly  the  crop  opens  into  the  second  portion  of  the  esophagus. 
Like  the  esophagus  the  crop  is  capable  of  great  distension. 

Structure. — The  wall  of  the  crop  is  composed  of  four  coats,  the 
mucous  membrane,  submucosa,  muscular  and  the  outer  fibrous. 

The  crop  is  lined  with  mucous  membrane  containing  mucous  glands 
which  secrete  a  mucus  to  keep  the  surface  moist.  The  surface  of  the 
mucous  membrane  is  covered  by  stratified  squamous  epithelium. 


SPLANCHNOLOGY  143 

The  submucosa  connects  the  mucous  membrane  to  the  muscular 
coat. 

The  wall  of  the  crop  is  provided  with  strong  muscles.  The 
fibrous  coat,  or  tunic,  connects  it  with  the  surrounding  structures^ 

Function. — The  crop  is  a  storehouse  for  the  food  during  the  hours 
of  feeding,  the  food  when  needed  by  the  stomach  being  gradually 
discharged  from  the  crop  by  the  contraction  of  its  muscular  walls. 
The  subcutaneous  cervical  muscles  which  cover  this  reservoir  aid  in 
this  discharge. 

In  the  act  of  deglutition,  the  food,  after  being  subjected  to  the 
fluid  supplied  in  the  mouth  by  the  adjacent  glands,  is  poised  upon 
the  tongue  and  swallowed  partly  by  a  sudden  jerk  of  the  head,  and 
partly  by  means  of  the  pressure  of  the  tongue  against  the  hard 
palate,  the  food  then  passes  down  the  esophagus  and  lodges  first 
in  the  crop,  till  needed  by  the  stomach,  when  it  is  passed  through  the 
second  portion  of  the  esophagus  to  the  first  portion  of  the  stomach, 
the  proventriculus.  The  time  during  which  food  remains  in  the 
crop  depends  upon  the  nature  of  the  food.  Animal  food  will,  in 
part,  be  retained  about  eight  hours  and  vegetable  foods  may  not  all 
be  passed  on  for  from  sixteen  to  eighteen  hours. 

The  Stomach  (Fig.  31,  No.  7;  Fig.  32,  B).— The  stomach,  or 
ventriculus,  of  fowls  is  made  up  of  two  portions,  namely,  the  pars 
glandularis,  or  proventriculus,  and  the  pars  muscularis,  or  gizzard. 

The  Proventriculus.  Location. — The  proventriculus  lies  in  the 
superior  part  of  the  groove  formed  by  the  two  lobes  of  the  liver,  is 
inferior  to  the  aorta,  and  is  directed  slightly  to  the  left,  communicat- 
ing anteriorly  with  the  second  portion  of  the  esophagus  and  poste- 
riorly emptying  into  the  pars  muscularis,  the  gizzard. 

Shape. — The  proventriculus  is  round  transversely  and  elongated, 
in  fact,  nearly  fusiform.  In  the  hen  of  average  size  it  measures  about 
1.62  inches  long  and  0.8  inch  in  diameter. 

Structure. — The  wall  of  the  proventriculus  has  four  coats,  the 
mucous,  submucous,  muscular,  and  serous. 

The  inner  mucous  coat  which  is  raised  in  folds,  is  lined  with 
columnar  epithelial  cells.  The  mucous  membrane  contains  lymph- 
oid  tissue.  The  mucous  coat  throughout  contains  simple  tubular 
glands  which  secrete  a  highly  acid  fluid  which  finds  its  way  to  the 
surface  through  small  cylindrical  ducts  lying  at  right  angles  to  the 
inner  surface  of  the  mucous  membrane  (Fig.  32,  No.  B,  i). 


144 


ANATOMY   OF   THE   DOMESTIC   FOWL 


FIG.  32. — Gizzard  and  stomach  of  the  fowl. 

A.  i,  Alveolar  glands.     2,  Mucous  membrane  of  the  inner  surface  of  the  pro- 
ventriculus  showing  the   tubular   glands.     3,    Connective   tissue   between   the 
alveolar  glands.     4,  An  artery.     5,  Muscularis  mucosa. 

B.  Photograph  of  the  proventriculus  and  gizzard.      I,  Proventriculus  showing 
stomata  of  glands.     2,  End  of  duodenum.     3,  Gizzard  showing  hornified  epithe- 
lium formed  into  grooves.     4,  The  heavy  muscular  walls. 


SPLANCHNOLOGY  145 

The  submucosa,  connects  the  mucous  and  muscular  coats  and 
the  muscularis  layer  throws  the  mucous  membrane  into  folds. 

Outside  the  muscularis  mucosa  there  is  another  layer  (Fig.  32, 
A),  of  simple   tubular  glands,  grouped  in  lobules,   and  lined  ~By~ 
cuboidal  cells  and  separated  from  each  other  by  clefts.     These 
tubular  glands  converge  toward  the  center  and  open  into  the  same 
cavity. 

The  middle  muscular  coat  can  be  divided  into  three  layers: 
two  thin,  longitudinal  layers,  and  a  thick,  circular  layer  interposed 
between  the  other  two. 

Function. — The  function  of  the  proventriculus  appears  to  be 
to  soak  the  food  with  a  secretion.  The  secretion  from  the  proven- 
triculus is  similar  to  that  produced  by  the  fundus  glands  of  the 
stomach  of  mammals.  It  contains  acid  and  a  ferment-pepsin. 

The  Gizzard  (Fig.  31,  No.  18).  Location. — The  gizzard,  or  mus- 
cular stomach,  occupies  a  portion  of  the  central  part  of  the  abdominal 
cavity  (Fig.  33,  No.  4).  It  lies  slightly  to  the  left  and  just  behind 
the  liver,  the  proventriculus,  and  the  spleen,  and  rests  upon  a  mass 
of  intestines.  The  gizzard  communicates  at  its  anterior  portion 
with  the  proventriculus  and  with  the  duodenum.  These  openings 
are  close  together.  The  gizzards  of  a  large  number  of  hens  of 
average  size  averaged  in  weight  as  follows:  full,  0.215  pound; 
empty,  0.126  pound.  The  gizzard  stands  perpendicularly  and 
somewhat  obliquely  in  the  abdominal  cavity. 

Shape. — In  shape  the  gizzard  is  roundish,  flattened  laterally. 

Structure. — The  walls  of  the  gizzard  are  very  thick  and  are  made 
up  of  three  coats:  mucous,  muscular,  and  serous. 

The  cavity  of  the  gizzard  is  covered  by  a  thick  skin-like  structure 
possessing  a  heavy  stratified  squamous  epithelial  layer  which  is 
thrown  somewhat  into  ridges  (Fig.  32,  B).  This  membrane  becomes 
thinnest  near  the  edges. 

The  mucous  membrane,  being  cornified  and  readily  detachable, 
is  by  some  anatomists  considered  as  a  special  membrane  (Fig. 
37,  B). 

At  the  pyloric  opening  there  is  a  valve  formed  by  a  fold  of  the 
mucous  membrane,  which  prevents  grit  and  large  particles  of  food 
from  passing  out  of  the  gizzard. 

On  each  side  it  has  a  powerful  fleshy  muscle,  the  muscularis 
lateralis.     These  musculares  laterales  are  hemispherical,  consist  of 
very  closely  packed  fibers  extending  transversely,  and  are  attached 
10 


146 


ANATOMY   OF    THE   DOMESTIC   FOWL 


to  strong  anterior  and  posterior  ligamentous  tendons.     They  are 
joined  at  the  edge  of  the  organ  by  a  strong  aponeurosis.     The 


FIG.  33. — View  of  viscera  of  the  left  side  of  a  hen.  i.  The  base  of  the  heart. 
2,  Proventriculus.  3,  Left  lobe  of  the  liver.  4,  Gizzard.  5,  End  of  the  duo- 
denal loop.  6,  Pancreas.  7,  Free  portion  of  the  small  intestine.  8,  Lungs. 
9,  Diaphragm. 


FIG.  34. — View  of  the  viscera  of  the  right  side  of  a  hen.  i,  Base  of  the  heart. 
2,  Lungs.  3,  Right  lobe  of  the  liver.  4,  Duodenal  loop.  5,  Pancreas.  6, 
Caecum.  7,  Large  intestine  or  rectum.  8,  Free  portion  of  the  floating  small 
intestine.  9,  Gall-bladder.  10,  Right  kidney,  n,  The  ribs.  Note  the  lungs 
pushing  up  between  them. 

muscular  fibers  are  red  but  do  not  possess  cross  striations;  they  are 
of  the  smooth   type.     The  muscularis  intermedii,  thinner  and  less 


SPLANCHNOLOGY 


147 


developed  than  the  musculares  laterales,  occurs  on  each  of  the 
anterior  and  the  posterior  parts  of  the  gizzard. 

The  serous  coat  covers  over  the  greater  part  of  the  external  sur- 
face of  the  gizzard  and  closely  adheres  to  the  muscular  coat. 

Function. — The  hard  callous  pads  of  the  gizzard,  operated  by  the 
powerful  muscles  above  described,  together  with  grit,  act  like  mill 
stones  and  make  reduction  to  fineness  very  complete. 

At  the  posterior  part  there  is  a  sacculated  portion  containing 
glands  of  the  long  tubular  type  which  secrete  a  fluid  ferment 


FIG.  35. — A  median'  antero-posterior  section  through  the  body  of  a  i -pound 
pullet,  i,  First  portion  of  the  esophagus.  2,  Crop.  3,  Second  portion  of  the 
intestine.  4,  Proventriculus.  5,  Gizzard.  6,  Spleen.  7,  Liver.  8,  Heart. 
9,  Point  where  duodenum  was  severed  from  gizzard.  10,  Point  where  duodenum 
was  severed,  n,  Duodenum.  12,  Pancreas.  13,  Caecum.  14,  Floating  small 
intestine.  15,  Ovary.  16,  Oil  sac. 

similar  to  that  secreted  by  the  glands  of  the  pyloric  portion  of  the 
stomach  of  mammals.  These  glands  also  exist  in  a  small  band  near 
the  entrance  of  the  gizzard.  Here  the  food  is  mixed  with  strongly 
acid  secretion  containing  pepsin  which  makes  gastric  digestion 
perfect. 

The  Small  Intestine  (Fig.  31,  No.  8  and  9). — The  small  intestine, 
intestinum  tenue,  is  the  tube  which  connects  the  gizzard  with  the 
large  intestine.  It  is  divided  into  two  parts,  the  duodenum  and  the 
free  portion.  Of  the  three  parts  as  considered  in  the  mammalian 


148 


ANATOMY    OF    THE   DOMESTIC   FOWL 


intestine,  only  the  first,  the  duodenum,  can  be  distinguished.  There 
is  no  demarcation  between  the  jejunum  and  the  ileum.  The  je- 
junum and  the  ileum  or  that  part  which  represents  these  sections, 
are  in  coils  suspended  from  the  free  border  of  the  mesentery  the 
other  border  of  which  is,  in  turn,  attached  to  the  dorsal  wall  (Fig. 
64).  The  length  of  the  small  intestine  in  a  hen  of  average  size  is 
about  61.7  inches. 


FIG.  36. 

A.  Section  of  the  duodenum  of  the  fowl,     i,  Villus.     2,  Gland.     3,  Mass  of 
lymphoid  tissue.     4,    Muscularis  mucosa.     5,  Longitudinal  layer.     6,   Circular 
muscular  layer.     7,  Serous  layer. 

B.  A  section  from  A  at  a.     i,  The  striated  free  border  of  the  cells.     2,  Goblet 
cell.     3,  Columnar  cell.     4,  Nucleus  of  cell. 

The  wall  of  the  small  intestine  is  provided  with  four  coats,  as 
follows :  a  mucous,  submucous,  muscular  coat  made  up  of  two  layers 
—the  outer,  longitudinal  and  the  inner  circular  layer,  and  an 
external  serous. 

The  mucous  membrane  which  lines  the  intestine  is  thick,  soft,  and 
highly  vascular.  It  has  a  velvety  appearance,  due  to  numerous  long, 
thin  projecting  mill.  The  villi  (Fig.  36,  A)  are  concerned  in  the 
absorption  of  the  digested  food,  absorbing  principally  the  emulsified 
fats.  Each  villus  is  covered  with  a  single  layer  of  high  columnar 
epithelial  cells.  Some  of  these,  the  so-called  goblet  cells,  provide 


SPLANCHNOLOGY 


149 


mucin  which  lubricates  the  mucous  surface.  These  cells  are  found 
in  all  mucous  surfaces  and  prevent  the  surface  from  becoming  dry. 
There  are  a  few  goblet  cells  near  the  summits  of  the  villi.  Open- 


FIG.  37. — Histological  studies  of  various  anatomical  parts. 

A.  A  transverse  section  of  the  first  portion  of  the  esophagus  of  a  fowl.      I, 
The  outer  longitudinal  muscular  layer.     2,  The  circular  muscular  layer.     3,  The 
submucosa.     4,  The  muscularis  mucosa.     5,  Stroma.     6,  Epithelial  layer.     7, 
The  lenticular  glands.     8,  The  lumen. 

B.  A  transverse  section  of    the  proventriculus.     i,   The  outer  longitudinal 
muscular  layer.     2,  The  middle  muscular  layer.     3,  The  inner  longitudinal  mus- 
cular layer.     4,  Stroma.     5,  The  muscularis  mucosa.     6,  The  submucosa.     7, 
Stroma.     8,  Tubular  glands.     9,  Tubulo-alveolar  glands.     10,  A  tubulo-alveolar 
gland  with  the  tubular  glands  cut  transversely,     n,  The  lumen  of  the  proven- 
triculus. 

C.  A  section  of  the  inner  wall  of  the  gizzard,     i,  The  hyaline  mucous  mem- 
brane.    2,    Branched  tubular  glands.     3,  Submucosa.     4,   Muscle.     5,  A  con- 
nective tissue  septum. 

D.  A  transverse  section  of  the  small  intestines,     i,  The  outer  longitudinal 
muscular   layer.     2,    The   inner   circular   muscular  layer.     3,    The   muscularis 
mucosa.     4,  The  stroma.     5,  Brunner's  glands.     6,  A  villus.     7,  Mass  of  lym- 
phoid  tissue. 

E.  A  transverse  section  through  the  cecum.     i,  The  outer  longitudinal  mus- 
cular layer.     2,  The  inner  circular  muscular  layer.     3,  The  submucosa.     4,  The 
muscularis  mucosa.     5,  The  stroma.     6,  Tubular  glands.     7,  The  lumen. 

F.  The  cerebellum  showing  the  arbo-vitae.       i,  White,  fiber  portion.     2,  The 
granular  layer.     3,  The  layer  of  Purkinje  cells.     4,  The  molecular  layer. 

ings  of  simple  intestinal  tubular  glands  the  duodenal  glands,  or  the 
glands  formerly  known  as  Brunner  's  glands,  are  located  between  the 
villi.  These  glands  secrete  the  succus  entericus,  or  intestinal  juice. 
These  openings,  or  stomata,  are  lined  with  granular  cells.  The 


ISO  ANATOMY   OF    THE   DOMESTIC   FOWL 

reaction  of  the  contents  of  the  small  intestine  is  strongly  acid,  but 
gradually  less  so  in  proportion  to  the  distance  down  the  intestinal 
tract  until  the  caeca  are  reached,  where  the  reaction  is  found  to  be 
faintly  acid,  neutral,  or  slightly  alkaline. 

Function. — The  function  of  the  small  intestine  is  that  of  digestion 
and  absorption. 

The  Duodenum.  Location  and  Shape. — The  duodenum,  a  small 
tube,  originates  from  the  gizzard  about  %  inch  to  the  right  of 
the  entrance  of  the  proventriculus.  Extending  from  left  to  right, 
it  passes  under  and  behind  the  gizzard  along  the  inner  side  of  the 
right  abdominal  wall  backward  to  the  posterior  portion  of  the  wall, 
and  a  trifle  more  than  half  way  toward  the  left  side,  where  the  loop 
rests.  This  loop,  the  duodenal  loop,  is  about  5  inches  in  length  (Fig. 
31,  No.  8).  The  two  branches  of  the  loop  the  first  and  the  second 
portions  or  the  descending  and  ascending  limbs,  are  loosely  held  by 
connective  tissue,  and  have  the  pancreas  lodged  between  them. 

The  Free  Portion  of  the  Small  Intestine.  Location. — That  sec- 
tion of  the  small  intestine  following  the  duodenum  is  called  the  free 
portion  of  the  small  intestine  and  occupies  the  space  between  the 
abdominal  air-sac  and  the  median  line  of  the  abdominal  cavity. 
It  is  disposed  in  coils  and  is  suspended  from  the  dorsal  wall  of  the 
abdomen  by  a  thin  membrane,  the  mesentery. 

The  bile  ducts  enter  the  small  intestine  about  14  inches  from 
its  point  of  origin.  The  pancreas  also  pours  its  contents  into  the 
small  intestine. 

The  Large  Intestine  (Fig.  31,  No.  12).  Location. — The  large 
intestine  extends  in  a  straight  line  along  the  inferior  border  of  the 
vertebral  column  communicating  anteriorly  with  the  small  intestine, 
and  the  caeca  and  posteriorly  with  the  cloaca. 

Shape. — The  diameter  of  the  large  intestine  is  approximately 
twice  that  of  the  small  intestine.  In  fowls  of  average  size  its  mean 
length  is  4.61  inches.  The  large  intestine  has  sometimes  been  spoken 
of  as  the  rectum,  or  straight  gut. 

Structure.— Like  the  small  intestine  the  large  intestine  has  four 
coats:  an  inner  mucous,  a  submucous,  a  middle  muscular  and  an 
outer  serous.  The  folds  of  mucous  membrane  of  the  large  intestine 
have  tubular  glands  lined  with  columnar  cells  (Fig.  37,  A  No.  i). 

Function. — The  lapge  intestine  is  similar  in  function  to  that  of  the 
small  intestine,  in  that  digestion  and  absorption  may  take  place 
within  it. 


SPLANCHNOLOGY  151 

The  Caeca  (Fig.  31,  No.  n).  Location. — The  fowl  has  two  caeca 
extending  forward  from  their  point  of  origin  at  the  juncture  of  the 
small  and  large  intestine. 

Shape. — The  caeca  average  7.61  inches  in  length.  They  are  targe 
in  caliber  toward  the  blind  extremity  and  are  constricted  near  their 
origin. 

Structure. — The  parietal  coats  are  continued  from  the  small 
intestine. 

Ebarth  has  described  an  elevated  body  in  the  caecum,  which  is 
located  about  4  millimeters  from  the  opening  and  is  composed  en- 
tirely of  lymphoid  tissue. 


FIG.  374- — Photomicrograph  of  a  transverse  section  of  large  intestine  and 
oviduct  just  anterior  to  the  cloaca,  showing  the  tubular  glands,  of  the  large  intes- 
tines, mucosa  of  oviduct  with  intervening  structures,  i,  The  tubular  glands  of 
large  intestine,  or  rectum.  2,  Muscular  wall  of  intestine.  3,  Wall  of  the  ovi- 
duct. 4,  Mucosa  of  the  oviduct. 

The  caeca  are  usually  partly  filled  with  a  soft  pultaceous  material 
of  a  pasty  consistency. 

The  Cloaca  (Fig.  31,  No.  13).  Location. — The  rectum  opens  by  a 
circular,  valvular  orifice  into  the  dilated  portion  just  in  front  of  the 
anus,  which  dilatation  is  called  the  cloaca. 

Shape. — The  cloaca  is  saccular  in  shape. 

Structure. — The  cloaca  is  divided  into  two  portions,  the  copro- 
deumal  and  the  urodeumal.  That  portion  of  the  cloaca  into  which 
the  intestine  empties  is  called  the  coprodeum;  and  the  ureter  and 


152  ANATOMY   OF    THE   DOMESTIC   FOWL 

oviduct  empty  into  the  urodeum.  The  seminiferous  tubules, 
carrying  the  semen  from  the  testes  in  the  male  empty  in  teat- 
like  projections  on  the  cloacal  mucous  membrane  into  the  urodeu- 
mal  portion.  The  cloacal  walls  are  similar  in  structure  to  the  large 
intestines. 

On  the  dorsal  wall  of  the  cloaca  between  it  and  the  spine,  is  a 
small  sac,  called  the  bursa  ofFabricius,  which  has  a  duct  communicat- 
ing with  the  cloaca.  The  mucous  membrane  of  this  sac  is  thrown 
into  folds  and  is  studded  with  glands.  The  bursa  of  Fabricus  is 
larger  in  the  young  than  in  the  adult  bird.  It  apparently  atrophies 
as  the  bird  becomes  older.  When  the  bird  is  four  months  old  this 
bursa  is  best  developed,  and  at  this  age  it  may  be  as  large  as  2  or  3 
centimeters  in  diameter. 

Function. — The  function  of  the  cloaca  is  to  give  passage  way  to 
the  feces,  the  urine,  and  the  egg  and  to  act  as  an  organ  of  copulation. 

Course  of  the  Food. — The  food  first  enters  the  mouth,  after  being 
picked  up  by  aid  of  the  beak.  From  here  it  passes  through  the 
pharynx  and  first  portion  of  the  esophagus  to  the  crop,  without 
mastication,  as  the  bird  is  not  provided  with  teeth.  The  food  is 
passed  from  the  crop  by  aid  of  its  muscular  walls  as  needed;  thence 
through  the  second  portion  of  the  esophagus  to  the  proventriculus, 
an  expansion  in  the  digestive  tube  just  before  it  terminates  in  the 
gizzard.  The  glands  of  the  proventriculus  produce  a  secretion  in 
which  the  food  is  soaked  before  passing  into  the  gizzard.  The 
gizzard  is  provided  with  strong  muscular  walls  which,  by  aid  of  grit, 
thoroughly  reduce  the  food  to  fineness.  From  the  gizzard  the  food 
passes  through  the  first  portion  of  the  small  intestine,  where  it  is 
subjected  to  the  action  of  the  bile  from  the  liver,  the  pancreatic 
juice  from  the  pancreas,  and  of  the  succus  entericus  from  the  glands, 
of  the  intestinal  wall.  The  food  is  then  passed  into  the  caeca.  The 
indigestible  portion  of  the  food  passes  from  the  caeca  through  the 
large  intestine,  or  rectum,  to  the  cloaca  and  thence  to  the  external 
world. 

The  digestive  functions  of  the  bird  are  very  potent  and  rapid. 
This  compensates  for  the  waste  caused  by  their  extensive,  frequent^ 
and  energetic  motions,  and  is  in  accordance  with  the  rapidity  of  their 
circulation  and  their  high  state  of  irritability. 

THE  ACCESSORY  ORGANS  OF  DIGESTION 

The  accessory  organs  of  digestion  are  the  liver,  pancreas,  and 
some  anatomists  include  also  the  spleen.  The  first  two  manufacture 


SPLANCHNOLOGY  153 

fluids  containing  ferments  which  aid  in  splitting  or  digesting  the 
food. 

The  Liver  (Figs.  31,  33  and  34).  Location. — The  liver,  hepar, 
lies  ventrally  and  posteriorly  to  the  heart.  It  is  related  anteriorly 
with  the  diaphragm,  inferiorly  with  the  sternum,  posteriorly  with 
the  gizzard  and  intestine,  and  superiorly  with  the  ovary,  oviduct 
and  proventriculus  and  laterally  with  the  abdominal  wall. 

Shape. — The  liver  is  a  voluminous  deep  livid  brown  gland,  soft 
and  friable  in  texture.  It  is  divided  into  two  principal  lobes,  a 
right  and  a  left. 

The  right  lobe  is  larger  than  the  left.  In  the  hen  of  average  size 
the  liver  weighs  35  grams.  The  parietal  surface  is  convex  and 
'smooth.  The  surface  which  lies  against  the  viscera  is  irregularly 
concave.  The  visceral  surface  furnishes  exit  for  the  bile  duct  and 
passage  for  the  nerves  and  blood-vessels.  This  part  is  called  the 
porta. 

The  left  lobe  may  be  cleft  from  below  so  deeply  as  to  form  two 
lobes  on  that  side. 

Structure. — Each  lobe  is  covered  by  a  double  serous  membrane, 
one  closely  adherent,  the  other  surrounding  the  structure  loosely. 
These  tunics,  which  are  reflections  of  the  peritoneum,  are  continued 
from  the  base  of  the  liver,  over  both  the  anterior,  and  the  posterior 
surface.  The  loose  layer  is  formed  by  the  air  cells  surrounding  the 
lobes.  The  thin  border  of  the  liver  is  usually  free. 

The  two  lobes  of  the  liver  are  connected  by  a  narrow  isthmus  of 
liver  tissue.  Occasionally  there  is  a  bird  in  which  there  occurs  a 
lobus  Spigelii  located  at  the  posterior  of  the  liver  between  the  two 
principal  lobes. 

The  apex  of  the  heart  sacculates  the  diaphragm  backward,  so  that 
part  of  this  apex  lies  between  the  right  and  the  left  lobes  (Fig. 
43,  No.  6  and  7).  A  ligament,  the  falciform,  extends  from  the  apex 
of  the  pericardial  membrane,  and  attaching  it  rather  firmly  to  the 
central  connective  tissue,  or  interlobar  ligament.  This  ligament 
also  has  attachments  to  the  inner  surface  of  the  sternum.  The 
broad  ligament  of  the  liver  is  formed  posteriorly  by  a  fold  of  the 
peritoneum. 

The  interlobar,  or  principal,  ligament  of  the  liver  is  formed  by  a 
large  and  strong  duplicature  of  the  peritoneum,  which  makes  a 
longitudinal  division  in  the  abdominal  cavity  similar  to  the  lateral 
division  made  by  the  thoracic  mediastinum  in  mammals.  It 


ANATOMY   OF    THE   DOMESTIC   FOWL 


is  reflected  upon  the  pericardium  from  the  linea  alba  and  the  middle 
line  of  the  sternum,  and  passes  deeply  into  the  interspace  of  the 
lobes  of  the  liver.  It  is  attached  to  these  lobes  throughout  their 
whole  length  and  connects  them  below  to  one  side  of  the  gizzard. 
The  lateral  and  posterior  part  of  the  liver  attach  to  the  adjacent  air 
cells,  and  the  whole  viscus  is  thus  kept  fixed  in  its  position  during 
rapid  and  violent  movements  of  the  bird. 

The  remains  of  the  umbilical  veins  are  traceable  within  the  dupli- 
cature  of  the  membranes  forming  the  septum.  These  remains  thus 
represent  the  round  ligament  of  mammals. 


FIG.  38. — Cellular  structure  of  liver,  pancreas,  and  trachea. 

A.  Liver,     i,  Liver  cells.     2,  Sinusoid.     4,  Nucleus  of  cells. 

B.  Pancreas,      i,  Island  of  Langerhans.     2,  Alveolar  cells.     3,  Duct. 

C.  Trachea.     I,    Ciliated   epithelia.     2,    Glands.     3,    Hyaline   cartilage. 

D.  Section  of  wall  of  ovum  at  Fig.  57  letter  d.     I.  Yolk.     2,  Granular  mem- 
brane.    3,  Theca.     4,  Blood-vessel. 

A  microscopic  study  of  the  liver  of  the  fowl  shows  a  compact  mass 
of  liver  cells  polyhedral  in  shape,  with  large  nuclei  (Fig.  38,  A). 
The  liver  tissue  differs  from  that  of  mammals  in  that  there  is  no 
clearly  outlined  lobular  arrangement;  neither  is  the  outline  of  the 
individual  cell  so  well  marked.  The  parenchymatous  portion  is 
made  up  of  columns  of  liver  tissue.  These  columns  anastomose  and 
show  narrow  channels  between.  They  are  best  seen  in  the  young 
chick. 

Function. — One  of  the  functions  of  the  liver  is  to  secrete  bile.  A 
gall-bladder,  which  receives  part  of  the  bile  secreted  by  the  right  lobe 
of  the  liver,  is  located  on  the  posterior  face  of  this  lobe.  Extending 


SPLANCHNOLOGY  155 

from  this  gall-bladder  there  is  a  duct,  the  cystic  duct,  which  empties 
into  the  small  intestine  toward  the  extremity  of  the  second  branch  of 
the  duodenal  loop.  Another  duct  called  the  hepatic  duct,  proceeds 
directly  from  the  two  lobes  of  the  liver  and  empties  into  the  intestine 
just  in  front  of  the  cystic  duct. 

The  Pancreas  (Fig.  31,  No.  17).  Location  and  Shape. — The  pan- 
creas, an  organ  lying  in  the  duodenal  loop  is  a  yellowish-white,  lobu- 
lated  gland,  elongated  in  shape.  Its  average  length  in  fowls  of 
average  size  is  4.96  inches,  and  the  average  weight  about  0.008  pound. 
The  pancreas  is  divided  into  lobes,  which  in  turn  are  divided  into 
lobules. 

Structure. — The  pancreas  has  a  supporting  connective  tissue. 
The  lobules  are  made  up  of  small  alveolar  glands,  which  are  lined 
with  columnar  epithelial  cells.  The  ducts  leading  from  the  alveoli 
are  small;  these  unite  to  form  larger  ducts  in  which  the  epithelium 
is  taller.  Between  the  alveoli  throughout  the  pancreas  there  are 
clusters  of  polyhedral  cells  which  form  the  islands  of  Langerhans. 
These  islands  are  said  to  produce  an  internal  secretion,  or  hormone, 
which  is  absorbed  by  the  blood  or  lymph  capillaries  and  thus  enters 
the  circulation  (Fig.  38,  B). 

Function. — The  function  of  the  pancreas  is  to  secrete  a  fluid  con- 
taining digestive  ferments. 

The  Spleen  (Fig.  31,  No.  21).  Location. — The  spleen,  or  lien, 
lies  in  a  triangle  formed  by  the  proventriculus,  the  liver,  and  the 
gizzard. 

Shape. — It  is  a  reddish-brown  body  shaped  like  a  buckeye,  is  small 
in  size,  weighing  only  about  0.005  pound. 

Structure. — The  outer  surface  of  the  spleen  is  covered  by  a  reflec- 
tion of  the  peritoneum.  After  this  covering  is  removed,  there  is 
observed  a  firm,  white,  fibrous  layer,  the  cortical  portion.  This 
covering  sends  into  the  interior  small  and  large  trabeculae,  forming 
a  framework  and  dividing  it  into  acini,  or  compartments.  The 
spaces  are  filled  with  a  dark  red  parenchymatous  material  called 
splenic  pulp.  The  framework,  in  both  deep  and  surface  portions, 
are  found  elastic  fibers  and  smooth  muscular  fibers. 

The  spleen  is  essentially  a  lymphatic  organ,  its  peculiar  structure 
depending  largely  upon  the  arrangement  of  the  blood-vessels. 
Compact  lymphatic  tissue  occurs  in  the  spleen  in  spherical,  oval,  or 
cylindrical  collections  of  closely  packed  lymphoid  cells.  These 
masses  are  known  as  the  Malpighian  bodies,  or  splenic  corpuscles. 


156  ANATOMY    OF    THE   DOMESTIC   FOWL 

They  are  distributed  throughout  the  splenic  pulp.  Each  splenic 
corpuscle  contains  one  or  more  small  arteries.  These  extend  near 
the  periphery  of  the  corpuscle  and  more  rarely  in  the  center. 

The  splenic  artery  passes  in  and  the  splenic  veins  out  at  the 
hilum  which  is  located  on  the  concave,  or  attached,  side  of  the 
spleen.  The  splenic  artery,  upon  entering  the  organ,  at  once 
branches,  the  trabeculae  forming  a  support  for  the  vessels. 

After  the  arteries  have  entered  the  hilum,  as  stated  above,  they 
divide  into  many  branches  which  follow  the  septa  of  the  connective 
tissue.  At  first  the  arteries  are  accompanied  by  branches  of  the 
splenic  veins.  Soon,  however,  the  arteries  leave  the  veins  and  the 
septa,  and  penetrate  the  splenic  pulp.  In  the  splenic  pulp  the 
adventitia  of  the  smaller  arteries  assume  the  character  of  reticular 
tissue,  and  become  infiltrated  with  lymphoid  cells.  This  infiltration 
forms  masses  which  are  called  the  splenic  corpuscles,  or  Malpighian 
bodies.  The  terminal  arteries  break  up  into  capillaries,  which  still 
retain  an  adventitia,  and  empty  into  border  spaces,  or  sinuses, 
sometimes  spoken  of  as  ampullae.  These  sinuses  in  turn  empty  into 
cavernous  sinuses  of  the  splenic  pulp.  From  these  are  finally 
formed  the  venules;  and  the  collections  of  venules  form  the  splenic 
veins  through  which  the  blood  gains  exit  from  the  spleen. 

The  Abdominal  and  Pelvic  Cavities. — In  birds  the  abdominal 
cavity  is  divided  into  two  smaller  cavities  by  a  fibrous  septum.  The 
anterior  cavity  representing  the  abdominal  contains  the  liver,  and 
the  other  representing  the  pelvic  contains  the  gizzard,  intestines  and 
oviduct. 

The  Peritoneum  and  the  Mesentery . — The  abdominal  and  pelvic 
cavities  are  lined  by  the  peritoneum.  Like  all  serous  membranes 
this  is  composed  of  a  parietal  and  a  visceral  portion,  which  together 
form  a  complete  sac,  with  the  organs  it  covers  situated  on  the  outer 
side.  The  peritoneum  like  other  serous  membranes  consists  of  a 
mesothelial  and  a  submesothelial  portion,  the  cells  of  the  former 
being  arranged  in  a  single  layer.  Since  a  serous  membrane  is  so 
arranged  as  to  line  a  closed  cavity,  and  at  the  same  time  to  cover 
its  contents,  it  follows  that  the  entire  membrane  must  be  a  closed 
sac,  the  mesothelial  layer  being  on  the  inside;  such  a  sac  is  called 
a  serous  sac,  or  cavity.  Synovial  membranes  are  also  regarded  as 
a  variety  of  serous  membranes.  The  fold,  or  layer,  of  the  mem- 
brane which  lines  the  cavity  is  called  the  parietal,  that  which 
covers  the  greater  part  of  the  organs  contained  therein  is  called  the 


SPLANCHNOLOGY 


157 


visceral  portion;  the  two  surfaces  contacting,  and  gliding  upon  each 
other,  are  lubricated  by  a  fluid  secretion  contained  in  the  sac;  hence 
one  use  of  these  membranes  is  to  prevent  friction  between  the  walls 
of  cavities  and  the  organs  contained  therein.  Serous  membranes 
line  the  abdominal  cavity,  pericardium,  cavities  of  the  heart  and  is 
continuous  throughout  the  vascular  structures. 


FIG.  39. — A  transverse  section  of  body  of  hen  through  15,  Fig.  34-  R,  Right 
side.  L,  Left  side,  i,  Spinal  cord.  2,  Esophagus.  3,  Trachea.  4,  Skin.  5, 
Pectoral  muscles. 

The  serous  membrane  besides  covering  the  external  surface  of  the 
viscera,  double  folds  pass  from  one  organ  to  another,  or  from  an 
organ  to  the  parietes  of  the  cavity.  These  double  folds  of  the 
peritoneum  are  known  as  ligaments,  or  as  mesenteries.  In  ligaments 
the  two  folds  are  strengthened  by  an  interposed  layer  of  fibre-elastic 
tissue.  A  mesentery  is  a  broad,  double  fold  of  peritoneum,  attached 
to  the  abdominal  parietes  above,  and  containing  a  portion  of  the 
intestine  in  its  free  or  remote  extremity.  Between  its  folds  we  find 
blood-vessels,  nerves,  and  lymphatics  or  lacteals,  hence  it  permits 


ANATOMY    OF    THE   DOMESTIC   FOWL 


vascular  and  nervous  communications  with  the  organ  attached  to  it. 
The  free  portion  of  the  small  intestine  is  attached  to  the  free  margin 
of  the  mesentery. 

THE  RELATIONS  OF  THE  VISCERAL  ORGANS  OF  THE 
DOMESTIC  FOWL 

Figure  33  shows  a  fowl  with  the  left  abdominal  wall  and  the  left 
thoracic  wall  removed.     No.  i  in  this  figure  shows  the  base  of  the 


FIG.  40. — Transverse  section  through  the  body  of  a  hen  through  14,  Fig.  34. 
R,  Right  side.  L,  Left  side,  i,  Spinal  cord.  2,  Esophagus.  3,  Trachea  near 
inferior  larynx.  4,  Lungs.  5,  Pectoral  muscles. 

heart  in  front  of  the  left  lobe  of  the  liver.  Above  the  liver  is  the 
proventriculus;  above  this,  the  diaphragm;  and  above  the  diaphragm 
and  the  base  of  the  heart  the  left  lung  occupying  the  superior  part 
of  the  thoracic  cavity,  and  that  there  is  no  distinct  pleural  sac,  as 
in  mammals  but  that  the  lung  pushes  out  between  the  ribs,  thus 
pressing  against  the  ribs  on  the  inner  and  the  lateral  sides.  The 
gizzard  is  back  of  the  liver,  to  the  left  side  of  the  abdominal  cavity, 


SPLANCHNOLOGY 


159 


and  beneath  and  in  front  of  the  duodenal  loop.     The  small  intestine 
from  this  side  is  above  the  gizzard.     Supero-anterior  to  the  gizzard 
is  the  blind  end  of  the  caecum.     The  pancreas  is  within  the  duodenal^ 
loop. 

Figure  34  shows  the  viscera  from  the  right  side  after  the  re- 
moval of  the  right  abdominal  and  the  right  thoracic  wall.  The 
base  of  the  heart  is  in  front  of  the  right  lobe  of  the  liver.  Above 


L,.-.  J 

FIG.  41. — Transverse  section  through  the  body  of  a  hen  at  12,  Fig.  33.  R, 
Right  side.  L,  Left  side,  i,  Spinal  cord.  2,  Esophagus.  3,  Inferior  larynx. 
4,  Base  of  the  heart.  5,  Aorta.  6,  Vena  cava.  7,  Lungs.  8,  Skin.  9,  Pec- 
toral muscles. 


these  the  right  lung  occupies  the  upper  part  of  the  thoracic  cavity  as 
in  the  preceding  illustration.  Just  back  of  this  is  the  anterior  lobe 
of  the  kidney.  The  gall-bladder  is  observed  at  No.  9  on  the  right 
lobe  of  the  liver.  Just  inferior  to  a  longitudinal  central  line  is  the 
duodenal  loop,  between  the  limbs  of  which  is  seen  the  pancreas. 
Above  this  loop  the  caeca  are  located.  The  gizzard  is  not  visible 


i6o 


ANATOMY   OF   THE   DOMESTIC   FOWL 


from  the  right  side;  on  this  side  posterior  to  the  liver  is  the  small 
intestine.     Superior  to  this  at  No.  7  the  rectum. 

The  relative  position  of  the  visceral  organs  in  the  median  line  is 
observed  in  Fig.  35.  No.  i  of  this  figure  shows  the  stump  of  the 
first  portion  of  the  esophagus,  and  No.  2,  the  left  wall  of  the  crop. 
Following  this,  and  located  just  below  the  vertebrae  is  the  second 


FIG.  42. — Transverse  section  through  the  body  of  a  hen  at  n,  Pig.  33.  R, 
Right  side.  L,  Left  side.  I,  Spinal  cord.  2,  Vertebra.  3,  Spinous  process 
of  vertebra.  4,  Lungs.  5,  Esophagus.  6,  Pericardial  sac.  7,  Sectioned  surface 
of  heart.  8,  Auricle  of  heart.  9,  Blood  clot  in  right  auricle.  10,  Section  of 
sternum,  n,  Pectoral  muscles. 

portion  of  the  esophagus.     The  major  portion  of  the  crop  is  located 
on  the  right  side. 

It  will  be  noted  that  the  second  portion  of  the  esophagus  passes 
over  the  base  of  the  heart  and  the  superior  part  of  the  liver,  and  then 
terminates  in  the  proventriculus.  The  proventriculus  extends  down- 
ward and  empties  into  the  gizzard.  This  organ  lies  antero-laterally 
to  the  gizzard,  supero-posterior  to  the  liver,  and  to  the  left  of  the 
spleen.  The  spleen  lies  in  a  triangle  formed  by  the  liver,  the  pro- 


SPLANCHNOLOGY  l6l 

ventriculus,  and  the  gizzard.  The  heart  is  noted  to  lie  supero-an- 
terior  to  the  liver,  and  between  the  anterior  portion  of  the  fissure 
formed  by  the  right  and  the  left  lobe.  The  ovary  is  located  back^of 
the  diaphragm  at  the  anterior  end  of  the  kidney  and  below  the  in- 
ferior surface  of  the  bodies  of  the  vertebrae.  The  bulk  of  the  floating 
portion  of  the  small  intestine  is  located  above  the  gizzard. 


i    mm 

FIG.  43. — Transverse  section  through  the  body  of  a  hen  at  13,  Fig.  34.  R, 
Right  side.  L,  Left  side,  i,  Spinal  cord.  3,  Body  of  vertebra.  3,  Superior 
spinous  process  of  vertebra.  4,  Lungs.  5,  Esophagus.  6,  Heart.  7,  Right 
and  left  lobes  of  liver.  8,  Sternum.  9,  Skin.  10,  Pectoral  muscles. 

A  transverse  anterior  section  of  a  normal  laying  hen  is  shown 
in  Fig.  39,  the  section  being  made  at  15  of  Fig.  34.  At  this 
point  the  esophagus  lies  centrally  and  above  the  trachea.  Figure 
40  shows  a  transverse  anterior  section  through  the  thoracic  region 
at  14  of  Fig.  34.  At  this  point  the  esophagus  is  slightly  to  the 
right  of  and  is  superior  to  the  trachea.  At  this  level  the  apex  of 
the  lung  is  sectioned.  This  is  in  the  region  of  the  cervical  air-sac. 
Figure  41  shows  a  posterior  section  at  12  of  Fig.  33.  The 
11 


162 


ANATOMY   OF   THE   DOMESTIC   FOWL 


esophagus  here  is  above  and  to  the  right  of  the  inferior  larynx,  and 
directly  below  and  between  the  lungs.  The  inferior  larynx  is 
above  the  base  of  the  heart. 

Figure  42  shows  a  transverse  anterior  section  made  at  n  of  Fig. 
33.  It  shows  that  at  this  level  the  esophagus  is  centrally  lo- 
cated and  passes  over  the  base  of  the  heart.  The  heart  occupies 


FIG.  44. — Transverse  section  through  the  body  of  a  hen  at  12,  Fig.  34.  R, 
Right  side.  L,  Left  side.  I,  Spinal  cord.  2,  Articular  surface  of  vertebral  seg- 
ment. 3,  End  of  rib.  4,.  Lungs.  5,  Proventriculus.  6,  Liver  showing  Glisson's 
capsule.  7,  Sternum.  8,  Pectoral  muscles.  9,  Skin. 


the  lower  portion  of  the  thorax  and  the  lungs  the  upper.  Figure 
43  shows  a  photograph  of  a  transverse  anterior  section  of  the  body 
made  at  13  of  Fig.  34.  At  this  level  the  apex  of  the  heart  lies 
within  the  anterior  fissure  of  the  liver.  The  sectioned  portion  of 
the  heart  shows  the  lower  portion  of  the  ventricle. 

In  this  figure  the  lungs  show,  on  the  sectioned  surface,  the  ends  of 


SPLANCHNOLOGY  103 

some  of  the  larger  bronchi.  The  esophagus  is  located  above  the 
heart.  Showing  the  relations  of  the  visceral  organs  back  of  the 
heart  girdle,  photograph  number  44,  gives  an  anterior  section  made 
at  12,  Fig.  33.  The  lungs  are  spread  out  occupying  the  posterior 
thoracic  region  and  below  at  No.  10  is  the  diaphragm.  The  dia- 
phragm does  not  appear  to  have  that  rigidity  and  firmness  of  position 


FIG.  45. — Transverse  section  through  the  body  of  a  hen  at  10,  Fig.  33.  R, 
Right  side.  L,  Left  side,  i,  Spinal  cord.  2,  Body  of  vertebra.  3,  Lungs, 
4,  Ova.  5,  Proventriculus.  6,  Liver.  7,  Sternum.  8,  Skin.  9,  Pectoral 
muscles. 


as  in  mammals.  It  is  rather  rudimentary.  Below  the  left  lung  and 
above  the  left  lobe  of  the  liver  is  the  proventriculus.  Note  that 
the  viscus  is  empty  and  that  the  mucous  membrane  is  thrown  into 
folds.  At  this  point  the  liver  occupies  much  of  the  abdominal 
cavity.  Figure  45  is  a  view  of  an  anterior  section  made  at  10, 


164 


ANATOMY    OF    THE   DOMESTIC   FOWL 


Fig.  33.  In  this  section  the  lungs  are  decreasing  in  caliber. 
The  liver  occupies  much  of  the  space  in  the  lower  right  abdominal 
quadrant,  and  above  and  to  the  right  is  the  ovary  with  many  of  the 
ova  developing  yolks.  Below  No.  4  which  is  a  developing  yolk,  is 
the  proventriculus.  Figure  46  is  a  view  of  an  anterior  section 


W- 

I 


FIG.  46.— A  transverse  section  through  the  body  of  a  hen  at  9,  Fig.  33.  R, 
Right  side.  L,  Left  side,  i,  Spinal  cord.  2,  Vertebra.  3,  Kidneys.  4,  Ovary. 
5,  Caecum.  6,  Small  intestine.  7,  Gizzard.  8  .Right  lobe  of  liver.  9,  Skin.  10, 
Pectoral  muscles. 

made  at  9,  Fig.  33.  At  this  level  are  shown  sectioned  surfaces 
of  the  kidneys,  which  lie  on  either  side  of  the  spinal  column.  Below 
the  spinal  column  and  occupying  the  left  upper  quadrant  is  the 
ovary  containing  ova  in  the  process  of  developing  yolks.  To  the 
right  is  the  sectioned  surface  of  one  of  the  caeca  and  below  this  and 
on  the  right  side  is  the  sectioned  ends  of  many  of  the  loops  of  the 


SPLANCHNOLOGY  165 

floating  portion  of  the  small  intestine.  Occupying  the  left  lower 
quadrant  is  the  sectioned  surface  of  the  gizzard  and  on  the  abdominal 
floor  and  to  the  right  of  the  gizzard,  the  posterior  end  of  the  right 
lobe  of  the  liver. 


THE  RELATIONS  OF  THE  VISCERAL  ORGANS  OF  THE  BABY  CHICK 

There  is  approximately  47  per  cent,  of  the  yolk  retained  in  the 
abdominal  yolk  sac  of  the  baby  chick  at  hatching.     Figure  47 


FIG.  47. — An  antero-posterior  section  through  the  body  of  a  baby  chick  just 
hatched,  i,  Abdominal  yolk  sac.  2,  Gizzard.  3,  Liver.  4,  Heart.  5,  In- 
testines. 6,  Spinal  cord.  7,  Cerebrum.  8,  Cerebellum.  9,  Fat  in  the  post- 
occipital  region.  10,  The  thymus  gland. 

shows  a  photograph  of  a  longitudinal  section  through  a  baby  chick. 
This  figure  shows  all  the  posterior  portion  of  the  abdominal  cavity 
occupied  with  abdominal  yolk.  The  abdominal  viscera  are  pushed 
forward,  and  as  the  yolk  is  gradually  absorbed  the  visceral  organs 
gradually  occupy  their  normal  position. 

A  section  through  this  body  Fig.  47  at  A  is  shown  in  Fig. 
48,  A.  At  this  point  the  esophagus  appears  below  the  vertebral 
column.  Figure  48,  B,  a  section  through  the  body  at  Fig.  47,  B, 
shows  the  apex  of  the  lungs.  In  a  median  line  and  below  the  lungs 
is  the  esophagus.  Note  the  mucous  membrane  thrown  into  folds. 
Here  the  heart  is  sectioned,  showing  both  auricles  and  both  ventri- 


i66 


ANATOMY   OF   THE   DOMESTIC   FOWL 


FIG.  48. — Transverse  sections  of  the  body  of  a,  baby  chick  at  hatching.     R, 


Right  side.     L,  Left  side. 

A.  A  transverse  section  at  A,  Fig.  50.     i,  Spinal  cord. 
Entrance  to  thorax.     4,  Stubs  of  the  wings. 

B.  A  transverse  section  at  B,  Fig.  50.     i,  Spinal  cord. 
Lungs.     4,  Heart. 

C.  A  transverse  section  through  the  body  at  C,  Fig.  50.     i,  Spinal  cord.     2, 
Lungs.     3,  Esophagus.     4,  Liver.     5,  Heart. 

D.  A  transverse  section  at  D,  Fig.  50.     i,  Spinal  cord. 


3,  Liver.     4,  Gizzard.     5,  Intestine.     6,  Kidneys.     7,  Gall-bladder. 


2,  Esophagus.     3, 
2,  Esophagus.     3, 


2,  Proventriculus. 


SPLANCHNOLOGY 


167 


cles.  This  is  a  view  looking  forward.  Figure  48,  C,  is  a  view  of  a 
posterior  section  made  at  Fig.  47,  C.  It  shows  the  same  relations 
of  the  esophagus  and  lungs,  but  shows  at  this  level  both  the  right  and 


FIG.  49. — Transverse  section  through  the  body  of  a  baby  chick. 
E  at  E,  Fig.  50.     i,  Spinal  cord.     2,  Kidneys.     3,  Gizzard.     4,  Intestines. 
5,  Unabsorbed  yolk.     6,  Stubs  of  legs. 

F.  A  section  at  F,  Fig.  50.     i,  Spinal  cord.     2,  Kidneys.     3,  Intestine.     4, 
Unabsorbed  yolk. 

G.  A  section  at  Gt  Fig.  50.     i,  Anus.     2,  Umbilicus. 

the  left  lobe  of  the  liver.     Between  these  lobes  we  note  the  sectioned 
apex  of  the  heart.     Figure  48,  D  shows  a  posterior  ssctforjit  jFij 


1 68  ANATOMY    OF   THE   DOMESTIC   FOWL 

47,  D.  At  this  level  the  kidneys  are  above  and  inferolaterally 
to  the  spinal  column.  The  intestines  are  below  the  kidneys;  and  on 
the  left  side,  between  the  kidneys  and  left  lobe  of  the  liver,  and 
near  the  abdominal  wall,  is  the  proventriculus.  Occupying  the  ma- 
jor portion  of  the  inferior  abdominal  cavity  are  the  right  and  the 
left  lobe  of  the  liver,  and  between  these  the  anterior  border  of  the 
gizzard.  Note  the  gizzard  sitting  at  an  angle  inclining  toward 
the  left  side.  Figure  49,  E  shows  a  section  at  Fig.  47,  E.  Here 
the  gizzard  occupies  the  left  lower  abdominal  quadrant.  To  the 
right  are  the  intestines;  and  directly  above  the  gizzard  is  a  small 
portion  of  the  anterior  end  of  the  abdominal  yolk  sac.  Infero-lat- 
erally  are  the  kidneys.  Figure  49,  F,  shows  the  kidneys  similarly 
located  as  in  the  preceding;  and  just  below  is  the  rectum  suspended 
by  the  mesentery.  The  rest  of  the  cavity  is  occupied  by  the  ab- 
dominal yolk. 


THE  URO -GENITAL  SYSTEM 

The  uro-genital  apparatus,  or  apparatus  uro-genitalis,  consists 
of  two  groups  of  organs:  the  urinary  and  the  genital.  The  former 
elaborate  and  remove  tlie  chief  excretory  fluid,  the  urine;  and  the 
latter  serve  for  the  formation,  development,  and  expulsion  of  the 
products  of  the  reproductive  glands. 

THE  URINARY  APPARATUS  (Fig.  50  and  Fig.  51). 

The  urinary  apparatus  of  the  bird  consists  of  two  kidneys,  from 
each  of  which  a  ureter  extends  and  empties  into  the  cloaca. 

The  Kidneys.  Location. — The  kidneys  are  located  in  excavations 
in  the  pelvic  roof.  They  are  related  internally  with  the  posterior 
aorta  and  vena  cava,  supero-internally  with  the  lumbo-sacral  ver- 
tebrae and  superiorly  and  supero-externally  with  the  ilium.  The 
abdominal  visceral  organs  lie  below  the  kidneys.  The  kidneys  are 
external  to  or  above  the  peritoneum. 

Shape. — In  the  fowl  of  average  size  the  kidneys  are  2%  inches 
long  and  are  made  up  of  three  irregular  lobes.  The  anterior  lobe 
is  usually  the  largest  and  the  middle  the  smallest.  The  anterior 
border  of  the  first  lobe  is  located  opposite  the  last  true  dorsal  articu- 
lation. The  anterior  lobe  is  called  the  anterior  pelvic  or  ilio-lumbar 
lobe,  the  middle  the  middle  pelvic  or  ilio-sacral  lobe,  and  the  posterior 
the  posterior  pelvic  lobe. 

Structure. — The  whole  kidney  has  a  fine  transparent  covering. 
The  dark,  brownish-red  parenchyme  can  be  seen  through  this  mem- 
brane. It  has  a  blood  vascular  system  and  a  urinary  tubular  sys- 
tem. The  larger  arteries,  the  veins,  and  the  nerves  pass  between  the 
lobules,  and  the  smaller  vessels  between  the  tubules.  These  form 
fine  network  or  plexuses.  The  lymphatic  vessels  are  very  few,  and 
are  mainly  found  on  the  surface.  The  kidneys  are  pierced  in  their 
posterior  third  by  the  external  iliac  artery  and  at  about  its  middle 
by  the  venous  branches  forming  the  posterior  vena  cava. 

The  lobes  are  made  up  of  lobules,  which  are  plainly  perceptible 
from  the  external  surface.  Each  lobule  is  apparently  a  unit  within 
.  '  169 


ANATOMY   OF   THE   DOMESTIC   FOWL 

itself.  It  receives  its  blood  supply  from  small  branches  of  the 
renal  artery  and  is  made  up  of  a  cortical  or  peripheral  portion  which 
con  tarns  tie  glomerules  (Fig.  52,  A)  and  a  medullary  portion, 
which  is  made  up  of  tubules,  or  urinary  canals,  arteries,  veins,  and 
nerves. 


The  urinary  canals  are  divided  into  two  kinds,  namely,  the  outer 
and  the  inner  tubular  systems.  The  outer  canals,  called  the  tubula 
uriniferi  corticalis,  are  very  small  in  caliber  and  are  located  in  the 


THE   URO-GENITAL   SYSTEM 


171 


lobules.  The  renal  artery  (Fig.  53,  No.  B,  3)  breaking  up  into 
arterioles  in  the  kidney,  and  finally  reaching  the  cortical  portion 
of  the  lobules,  form  capillary  plexuses  in  the  shape  of  minute  spheres, 
which  are  the  glomerules  (Fig.  53,  No.  C,  3  and  B,  5).  Around  each 
glomerule  there  is  formed  a  capsule  called  Bowman's  capsule,  which 
is  the  beginning  of  the  uriniferous  tubule.  This  entire  mass  is  called 
the  Malpighian  body,  or  renal  corpuscle.  This  capsule  then  ex- 
tends as  the  urinary,  or  secreting  tubule,  being  at  first  constricted, 
then  convoluted,  and  terminates  into  a  second  portion,  the  descend- 


FIG.  51. — The  kidneys.  la,  The  posterior,  i&,  the  middle  and  ic,  the  anterior 
lobes  of  the  kidney.  2,  The  posterior  aorta.  3,  The  external  iliac  or  crural 
artery.  4,  The  ischiadic  artery.  5,  The  sacralis  media  artery.  6,  The  ureter 
which  empties  into  the  cloaca  at  7.  8,  The  external  iliac  vein.  9,  The  internal 
iliac  vein.  10,  The  iliacus  communis. 

ing  limb  of  Henle.  This  portion  of  the  tubule  becomes  constricted. 
It  then  forms  the  loop  of  Henle  and  ascends  as  the  second  portion, 
or  second  limb  of  Henle,  which  is  again  of  greater  diameter.  The  top 
of  the  secreting  tubule  is  slightly  wavy  and  empties  into  the  col- 
lecting tubule  along  with  many  others.  These  collecting  tubules 
in  turn  merge  into  large  tubules  which  finally  empty  into  the  ureter 
(Fig.  53,  No.  14).  These  collective  bundles  correspond  to  the  pyra- 
mids of  the  kidnevs  of  mammals. 


172 


ANATOMY   OF   THE   DOMESTIC    FOWL 


The  neck  of  the  uriniferous  tubule  as  it  emerges  from  Bowman's 
capsule  is  short  and  narrow  and  is  lined  with  a  few  cuboidal  cells. 


FIG.  52. 

A.  Photomicrograph  of  a  section  of  a  kidney  showing  three  lobules,     i,  Cor- 
tical portion  of  lobule  showing  glomeruli.     2,  The  central  or  medullary  portion 

o:    the  lobule.     3,  The  outer  surface  of  the  kidney. 

B.  Salts  from  the  urine  of  a  hen.     i,  Uric  acid  crystals.     2,  Sodium  urate 
crystals. 

Toward  the  glomerular  end  the  cells  are  of  a  transitional  form  gradu- 
ally merging  into   the  flat  squamous  type  peculiar  to  Bowman's 


THE    URO-GENITAL   SYSTEM 


capsule.  The  first  convoluted  tubule  is  lined  with  irregular  cuboidal 
or  pyramidal  epithelial  cells.  The  descending  limb  of  Henle's  loop 
is  narrow  and  is  lined  with  a  simple  layer  of  flat  epithelial  cells.____In 


A.  i 

tubule. 


3,   Collecting 


FIG.  53. — The  renal  structure. 

Capillary  blood-vessel.     2,  Descending  limb  of    Henle. 
4,  Ascending  limb  of  Henle. 

B.  i,  Branch  of  renal  artery.     2,  The  descending  or  medullary  branch.     3, 
The  ascending  branch.     4,  The  arteriole  taking  part  in  the  formation  of  the 
glomerule.     5,  The  glomerule.     6,  Bowman's  capsule.     7,  Blood-vessel  extending 
from  the  glomerule.     8,  The  vein  of  the  medullary  part  of  the  lobule.     9,  The 
neck.     10,  The   convoluted   tubule,     n,  The   descending  limb  of  Henle.     12, 
Henle's  loop.     13,  The  ascending  loop  of  Henle.     14,  The  collecting  tubule. 

C.  i,  Section  through  a  convoluted  tubule.     2,  Bowman's  capsule.     3,  The 
glomerule. 

the  loop  the  epithelium  changes  from  the  flat  type  in  the  descending 
limb  to  the  cuboidal  in  the  ascending  limb.  The  ascending  limb  of 
Henle's  loop  again  becomes  broader  and  is  lined  with  low  cuboidal 
cells.  The  second  convoluted,  or  tortuous,  tubule  is  lined  with  low 


174  ANATOMY   OF   THE  DOMESTIC  FOWL 

cuboidal  cells  as  are  also  the  collecting  tubules.  The  collecting 
tubules  originate  from  every  part  of  the  internal  substance  of  the 
lobules,  and  extending  to  the  gyrations,  uniting  in  the  pinniform 
structure  and  traversing  to  the  margin  of  the  lobules,  following  along 
the  uneven  surface,  infero-laterally  and  toward  the  median  body  line, 
finally  empty  into  the  ureter. 

There  are  many  arterial  branches  given  off  from  the  arteria  re- 
nalis.  The  arteries  which  supply  the  kidneys  are  given  off  from  the 
posterior  aorta  and  ischiadic  artery.  As  soon  as  these  arteries  enter 
the  kidney  they  break  up  into  two  systems.  One  system  supplies 
the  kidney  substance  with  nourishment  in  the  form  of  nutrient  blood; 
the  second  system  supplies  the  glomerules  with  what  may  be  con- 
sidered functional  blood  (Gadow).  The  second  system  of  arteries 
branches  into  the  small  arteria  interlobularis,  which  pass  between 
the  lobules  of  the  kidneys  where  they  give  off  side  branches  which 
penetrate  the  cortical  portion  of  the  lobules  and  form  the  capillary 
plexus,  the  glomerule. 

The  arteriole  that  enters  into  the  structure  of  the  glomerule  is 
lined  with  endothelial  cells  and  is  surrounded  by  a  few  muscle  fibers 
and  a  fine  network  of  connective  tissue.  The  vessel  that  carries  the 
blood  away  is  similarly  constructed. 

Function. — In  the  glomerules  the  liquid  portion  of  the  urine  is 
filtered  out  of  the  blood,  which  urine  flows  through  the  uriniferous 
tubules  and  passes  from  the  kidney  through  the  ureter.  In  the 
cubical  cells  are  extracted  the  solid  portions  of  the  urine  which  also 
pass  through  the  tubules  with  the  liquid.  The  urinary  secretion, 
as  found  in  the  ureter,  does  not  contain  much  liquid,  but,  on  the  con- 
trary, is  made  up  of  a  pasty  material  consisting  of  salts  which  are, 
for  the  most  part,  uric  acid  crystals  and  sodium  urate  (Fig.  52,  B). 
This  material  becomes  hard,  like  cement,  soon  after  being  exposed 
to  the  atmosphere.  This  secretion  may  be  noted  as  a  whitish  pasty 
material  on  the  outer  parts  of  the  feces,  or  droppings,  voided  by  the 
birds. 

The  Ureter.  Location. — The  ureter  extends  along  the  inferior  sur- 
face of  the  kidney.  It  has  its  origin  near  the  anterior  extremity  of 
the  kidney,  and  passing  posteriorly  the  entire  length  of  the  kidney 
receives  tributary  collecting  tubules,  and  terminates  in  the  upper 
wall  of  the  cloaca  in  the  urodeumal  portion. 

Shape. — The  ureter  gradually  enlarges  in  diameter  until  it  reaches 


THE   TIRO-GENITAL   SYSTEM  175 

the  posterior  border  of  the  kidney,  and  then  maintains  about  the 
same  caliber  throughout  the  rest  of  its  course. 

Structure. — The  ureter  wall  is  made  up  of  three  coats  as  follows: 
mucous,  muscular  and  fibrous. 

Function, — The  ureters  serve  as  a  passage  way  for  the  urine  from 
the  kidneys  to  the  cloaca. 

THE  MALE  GENERATIVE  ORGANS  (Fig.  54) 

The  male  generative  organs  in  the  fowl  consist  of  two  testicles 
and  an  excretory  apparatus,  the  vas  deferens,  for  each. 

The  Testicles.  Location. — The  testicles  are  located  in  the  sub- 
lumbar  region  of  the  abdominal  cavity,  behind  the  lungs,  below  the 
anterior  extremity  of  the  kidneys,  and  opposite  the  last  three  ribs. 


FIG.  54. — The  pelvic  organs  of  a  cockerel.     A,  Testes.     B,  Rectum.     C,  Cloaca. 
D,  Vas  deferens.     E,  Kidney.     F,  Adrenal  gland.     G,  Lungs.     H,  Ureter. 

Shape. — The  testicles  are  ellipsoid  in  shape;  their  size  varies 
with  the  different  species  of  birds.  The  two  in  the  same  bird  are 
usually  of  the  same  size,  though  one  testicle  may  be  slightly  larger 
than  the  other.  In  a  summary  of  a  large  number  of  weights  of  the 
testicles  of  ten  months  old  cockerels,  the  average  weight  was  0.021 
pound  each.  The  average  measurements  were  2  inches  in  the  major 
diameter  and  i  inch  in  the  minor  diameter.  In  the  cockerel  before 
sexual  maturity,  which  is  denoted  by  the  male  bird's  crowing,  the 
testicles  are  very  small.  They  resemble,  in  shape,  a  navy  bean  and 
are  yellowish-white  in  color. 


176  ANATOMY    OF    THE   DOMESTIC   FOWL 

Structure. — The  testicle  is  surrounded  by  a  thin  fibrous  capsule, 
which,  in  the  mature  cock,  is  very  vascular.  This  capsule  sends 
into  the  interior  of  the  gland,  septa  which  form  the  framework, 
or  supporting  structure.  This  framework  forms  the  spaces  in  which 
are  located  the  glandular  substance.  The  glandular  portion  consists 
of  the  tubuli  seminiferi,  which  are  lined  with  cubical  cells.  The 
framework  supporting  these  tubules  gives  passage  to  'arterial 
branches  of  the  spermatic  artery,  which  furnish  an  abundant  blood 
supply;  the  framework  also  supports  the  veins  returning  the  blood 
from  the  testicle.  The  seminiferous  tubules  end  in  blind  extremities 
in  the  epididymus  or  globus  minor,  and  unite  in  the  seminiferous 
canals.  All  arteries,  veins,  lymphatics,  and  seminiferous  tubules 
enter  or  leave  through  the  globus  minor  at  the  attached  portion  of 
the  testicle.  The  epididymis  is  made  up  largely  of  convoluted 
tubules  which  are  the  continuation  of  the  secreting  tubules  of  the 
globus  major.  The  walls  of  the  tubules  of  the  globus  minor  become 
thicker  and  are  provided  with  smooth  muscle  cells  in  addition  to 
the  connective  tissue  and  endothelial  lining.  The  convoluted 
tubules  empty  into  the  vas  deferens.  The  epididymus  is  covered 
by  the  fibrous  capsule;  which  corresponds  to  the  tunica  albuginea 
of  mammals  and  may  be  considered  as  a  reflection  or  modification 
of  the  visceral  peritoneum. 

The  substance  of  the  testicle  is  very  soft;  in  fact,  it  may  be  said 
to  be  of  the  consistency  of  encephaloid  material.  It  is  made  up 
of  secreting  tubules  in  which  are  found  the  spermatozoa;  it  also 
contains  cells  which  produce  an  internal  secretion,  or  hormone. 
There  is  also  produced  some  fluid  in  which  the  spermatozoa  float, 
the  whole  material  manufactured  constituting  the  semen. 

The  spermatozoa  of  the  fowl  are  provided  with  long  cylindrical 
bodies,  which  may  be  straight  or  wavy  (Fig.  55,  A).  The  body 
of  the  spermatozoon  is  obtuse  anteriorly,  and  posteriorly,  tapers 
into  a  filimentary  tail,  or  flagellum,  of  varying  length,  by  the  aid  of 
which  the  spermatozoon  moves  about  in  the  fluid. 

The  histological  structure  of  the  testicles  of  the  baby  chick  at 
hatching  is  approximately  one-half  white  fibrous  connective  tissue. 
The  seminal  tubules  are  small  and  widely  distributed  among  the 
connective  tissue.  The  cells  of  these  tubules  possess  rather  large 
nuclei,  round  in  shape,  with  linin  network  and  chromatin  granules, 
typical  of  resting  germ  cells.  As  the  bird  develops  the  testicles 


THE   URO-GENITAL    SYSTEM 


177 


FIG.  55- 

A.  Spermatozoa  of  a  cock,     a,  The  spermatozoa,     b,  The  head,     c,  The  tail. 

B.  The  oviduct  of  a  hen  removed.     A,  The  oviduct.     B,  The  superior  liga- 
ment.    C,  The  inferior  ligament.      Note  the  oviduct  thrown  in  folds  and  the 
anastomosing  blood-vessels. 

12 


178  ANATOMY  OF   THE  DOMESTIC  FOWL 

grow,  the  seminal  tubules  become  larger,  and  the  amount  of  con- 
nective tissue  correspondingly  less. 

In  addition  to  the  tubules,  the  spermatogenic  cells,  and  the 
connective  tissue,  there  is  also  in  the  testicles  more  or  less  fat. 
There  is  a  small  amount  of  connective  tissue  between  the  semi- 
niferous tubules,  in  which  locations  there  are  also  clusters  of  poly- 
hedral cells,  with  round  nuclei,  others  are  the  interstitial  cells. 

The  Vas  Deferens  (Fig.  54,  D}.  Location  and  Shape. — Extending 
from  the  epididymus,  is  the  vas  deferens  which  runs  backward 
on  the  infero-internal  surface  of  the  kidney  and  to  the  outside  of 
the  ureter.  It  is  very  tortuous  passing  on  the  infero-lateral  surface 
of  the  kidney  in  company  with  the  ureter  and  becoming  somewhat 
expanded  posteriorly  it  terminates  in  the  upper  wall  of  the  cloaca 
in  a  rather  small  papilla  located  in  the  uro-genital  portion  of  the 
cloaca  anterior  to  the  mouth  of  the  ureter.  This  papilla  is  the 
organ  of  copulation  and  in  ducks  is  very  large,  and  spirally  elongated, 
and  retractile  forming  a  kind  of  penis.  The  papilla  is  traversed 
by  a  furrow  on  the  upper  surface  through  which  the  semen  flows. 

Structure. — The  vas  deferens  is  covered  and  supported  by  the 
peritoneum.  Its  wall  is  made  up  of  a  fibrous  structure  in  which 
may  be  found  smooth  muscle  fibers.  The  wall  does  not  possess 
glands.  It  is  lined  with  columnar  epithelium.  The  posterior 
end  is  expanded  and  terminates  into  a  papilla.  The  base  of  the 
papilla  is  surrounded  by  a  plexus  of  arteries  and  veins,  which  serve 
as  an  erectile  organ  during  the  venereal  orgasm,  when  the  fossa 
of  the  turgid  papilla  is  everted,  and  the  semen  brought  into  contact 
with  the  similarly  everted  orifice  of  the  oviduct  of  the  female, 
along  which  the  spermatozoa  pass  by  undulatory  movements  of 
their  ciliary  appendage,  or  tail. 

THE  FEMALE  GENERATIVE  ORGANS  (Fig.  56) 

The  female  generative  organs  consist  of  one  ovary  and  an  oviduct. 

Location. — The  ovary  is  located  similarly  to  the  testicles  of  the 
male  bird,  in  the  sublumbar  region  of  the  abdominal  cavity,  just 
at  the  anterior  end  of  the  kidneys,  posterior  to  the  lungs,  and  slightly 
to  the  left  of  the  center. 

Shape. — In  the  pullet  the  ovarian  mass  appears  somewhat  like  a 
bunch  of  grapes,  being  made  up  of  from  3500  to  4500  small,  whitish 
spheres,  which  represent  the  undeveloped  ova,  and  which  in  the 


THE   URO-GENITAL   SYSTEM 


179 


active  state  are  developed,  one  by  one,  into  yolks  with  their  blasto- 
derms. From  the  blastoderm  the  fetus  may  later  be  developed. 
In  the  active  ovary  of  the  laying  hen  the  ovarian  mass  is  of  consider- 
able size,  as  it  contains  ova  in  different  stages  of  developmentr 
Only  one  ovum  is  completely  developed  at  a  time,  though  occasion- 
ally there  may  be  only  a  few  hours  between  the  maturity  of  succes- 


FIG.  56. — Functionating  female  generative  organs  of  a  hen.  i,  Ova  in  process 
of  formation  of  yolk.  2,  Stigmal  line  at  which  point  the  capsule  ruptures  when 
ovum  is  mature.  3,  The  funnel  end  of  the  oviduct.  4,  The  oviduct  torn  loose 
and  laid  to  one  side,  the  albumin-secreting  portion.  5,  The  shell  membrane 
secreting  portion.  6,  The  albumin.  7,  The  yolk.  8,  The  shell- secreting  por- 
tion. 9,  The  cloaca.  10,  The  rectum. 

sive   ova.     The   ova  receives  nourishment  from  the  blood-vessels 
of  the  capsule,  which  vessels  are  branches  of  the  ovarian  artery. 

Structure. — The  ovary  contains  very  vascular  cellulofibrous  tissue. 
The  ovum  as  it  develops  is  attached  to  the  ovarian  body  by  means 
of  a  delicate  white  fibrous  pedicle.  When  the  yolk  is  mature 
it  escapes  from  the  enveloping  fibrous  capsule  by  a  cleavage  of 
the  capsule.  The  cleavage  line  is  called  the  stigmen  (Fig.  56,  No. 


l8o  ANATOMY    OF    THE   DOMESTIC   FOWL 

5).  The  yolk  is  surrounded  by  a  very  delicate  membrane  called  the 
mtelline  membrane.  The  empty  sac  now  shrinks  and  finally 
disappears. 

The  Egg. — The  principal  divisions  of  the  egg  are  the  yolk,  the 
albumin  outside  of  the  yolk  content,  the  shell  membranes  and  the 
shell  (Fig.  58).  As  stated,  the  yolk  is  formed  in  the  ovary,  leaving 
the  other  three  portions  to  be  formed  in  the  oviduct. 


FIG.  57. — Section  through  the  ovary  of  the  hen.  a,  The  ova.  d,  An  ovum 
Beginning  to  receive  deposits  of  yolk  material,  c.  Ova  farther  advanced  in  yolk 
formation. 

The  albumin  may  be  subdivided  into,  first,  a  thin  layer  of  albumin 
lying  close  around  the  yolk;  second,  a  thick  layer  of  albumin  lying 
at  the  outer  periphery;  and  third,  a  modification  of  the  albumin 
called  the  chalazae.  The  chalazae  are  twisted,  dense  cord-like 
structures  at  either  pole  of  the  yolk,  one  end  of  which  is  adherent 
to  the  vitelline  membrane  and  the  other  to  the  inner  membrane 
surrounding  the  albumin.  The  chalazae  thus  act  as  stays  to  this 
structure,  whicrris  carrying  a  delicate  burden,  the  blastoderm. 


THE   URO-GENITAL    SYSTEM 


181 


The  shell  membrane  consists  of  two  layers,  an  inner  delicate, 
and  an  outer  thicker  layer.  When  the  egg  is  just  laid  these  two 
membranes  are  in  all  parts  closely  adherent  to  each  other,  and_the_ 
egg  content  completely  fills  the  shell  cavity.  As  soon  as  the  content 
cools  there  is  a  slight  contraction;  the  two  shell  membranes  separate 
at  the  large  end  of  the  egg,  forming  an  air  cell  which  gradually 
enlarges  as  the  evaporation  of  liquid  through  the  pores  of  the  shell 
takes  place. 

The  shell  consists  of  several  layers.     Three  are  easily  distinguish- 
able: first,  an  inner  mammillary  layer,  consisting  of  minute  conical 


FIG.  58. — A  diagram  of  the  parts  of  the  egg.  a,  The  blastoderm,  b,  The 
shell,  c,  The  outer  shell  membrane,  d,  The  inner  shell  membrane,  e,  The  air- 
sac  at  the  large  end  of  the  egg.  /,  The  albumin,  g.  The  chalaza.  h,  The 
yellow  layers  of  yolk,  i,  The  white  layers  of  yolk,  k,  The  flask-shaped  portion 
of  white  yolk.  /,  The  vitelline  membrane. 

deposits  of  calcareous  material;  second,  a  middle  spongy  layer, 
composed  of  a  thick  network  of  fibers;  third,  an  outer  delicate, 
cuticle-like  structure.  In  certain  breeds  of  poultry  a  pigment 
may  be  added;  for  example,  in  ducks  a  pea  green,  in  turkeys  a 
spotted  brownish  material,  and  in  fowls  pink  and  various  shades  of 
brown.  The  egg  shell  is  porous  to  admit  the  free  exchange  of  air 
during  the  process  of  incubation. 

An  average  sized  hen  egg  weighs  about  2  ounces,  of  which  n 
per  cent,  is  shell,  32  per  cent,  yolk,  and  57  per  cent,  white.  The 
principal  chemical  constituents  of  the  egg  are  as  follows:  ash,  or 
mineral  matter,  9  per  cent.;  fat,  or  hydrocarbon,  9.3  per  cent.; 
proteids,  or  nitrogenous  matter,  11.9  per  cent.;  and  water,  65.5 


1 82  ANATOMY   OF   THE   DOMESTIC   FOWL 

per  cent.  There  is  apparently  no  constant  proportion  of  weight 
between  the  yolk  and  albumin.  There  is  also  a  variation  in  the 
weight  of  the  shell  due  to  its  variation  in  thickness. 

In  an  examination  of  ten  eggs  of  average  size,  the  yolk  constituted 
31  per  cent,  of  the  total  weight  of  the  egg. 

The  following  is  the  result  of  the  analysis  of  twelve  eggs  of  average 
size.  This  analysis  included  the  shell  and  all  other  parts  taken 
together.1 

Moisture 64. 25  per  cent. 

Dry  matter 35-75  per  cent. 


100.00  per  cent. 

Parts  per  hundred  including  shell 

Protein 10.  2500 

Fat 10.6200 

Phosphorus 3020 

Calcium 6080 

Magnesium 0985 

Iron 0103 

Sulphur 3950 

Chlorine 1506 

Potassium 0103 

Sodium 2000 

The  Oviduct. — The  three  separate  and  distinct  portions  of  the 
egg,  albumin,  shell  membranes,  and  the  shell,  are  constructed  in 
different  parts  of  the  oviduct. 

Location. — The  oviduct  of  the  hen  extends  along  the  left  side  of  the 
bodies  of  the  vertebrae,  and  the  roof  of  the  pelvic  cavity  and  lies 
dorsal  to  the  abdominal  air-sac.  It  extends  from  the  posterior 
border  of  the  ovary  and  empties  into  the  cloaca  (Fig.  56,  No.  3  and 
8)  through  a  transverse  slit. 

Shape. — In  a  well-developed  Plymouth  Rock  pullet,  but  one 
whose  reproductive  organs  have  never  become  active,  the  oviduct 
is  about  4^  inches  long;  in  the  fully  developed  and  active  state  it 
is  from  18  to  20  inches  long,  and  in  a  collapsed  state  about  %  inch 
in  diameter.  It  is  held  in  position  by  two  ligaments,  a  dorsal  and 
a  ventral  (Fig.  55  B)  to  be  described  later.  The  oviduct  is  tortuous 
in  its  course,  forming  three  principle  convolutions  before  reaching 

1  The  analysis  was  made  by  D.  M.  McCarty,  chemist,  Animal  Industry 
Division,  North  Carolina  Experiment  Station. 


THE   URO-GENITAL   SYSTEM 


the  cloaca,  and  like  the  ovarian  mass,  in  its  active  state,  pushes 
the  abdominal  viscera  downward  and  toward  the  right  side. 

Structure. — The  oviduct  consists  of  three  coats:  first,  the  serous, 
located  on  the  outside,  which  is  a  reflection  of  the  peritoneum; 
second,  the  muscular  middle  tunic;  third, -the  mucous  coat,  which 
in  a  resting  state  is  thrown  into  folds. 


FIG.  59. — The  active  oviduct  of  a  hen  laid  open,  i,  The  ovary.  2,  The 
funnel.  3,  The  albumin  secreting  portion.  4,  The  isthmus.  5,  The  shell  gland 
portion.  6,  The  vagina.  7,  The  superior  ligament.  8,  The  inferior  ligament. 

Parts  of  the  Oviduct. — The  parts  of  the  oviduct  are  as  follows: 
the  funnel,  the  albumin-secreting  portion,  the  isthmus,  the  shell- 
gland  portion,  or  uterus,  and  the  vagina  (Fig.  59). 

The  funnel  is  the  trumpet-shaped  portion,  the  ostium  tubae 
abdominale,  whose  mouth  or  fimbriated  opening  faces  the  ovary, 
and  lies  ventrally  to  receive  the  ovum,  or  yolk,  as  it  is  discharged 
from  the  ovary.  Its  thin  wall,  expanded  in  the  anterior  portion, 
is  provided  with  fimbriae-like  projections.  This  funnel-shaped 
portion  soon  converges  to  form  a  constricted  portion.  This  por- 
tion of  the  active  oviduct  is  from  3  to  4  centimeters  long.  The 
mucous  membrane  occurs  in  folds  forming  low  longitudinal  spiral 


1 84 


ANATOMY   OF    THE   DOMESTIC   FOWL 


ridges  (Fig.  60,  A).  The  fimbriae  are  continuous  with  the  dorsal 
and  the  ventral  ligament  of  the  oviduct;  and  from  this  point, 
where  the  ridges  of  the  mucous  membrane  are  almost  nil,  they 
gradually  increase  in  height  as  they  extend  down  the  tube.  These 
ridges  are  continued  in  those  of  the  second,  or  albumin-secreting 
portion  (Fig.  60,  D).  At  this  point  they  increase  in  height  very 
rapidly.  Here  the  bundles  of  muscular  fibers  of  the  middle  coat 
are  thin  and  distributed  among  bundles  of  connective  tissue.  The 
muscular  fibers  consist  of  two  layers,  an  outer  longitudinal  and  an 


FIG.  60. — The  mucous  lining  of  the  oviduct. 

A.  Transverse  section  of  the  oviduct  wall  in  the  region  of  the  neck  of  the 
funnel  showing  primary  and  secondary  folding  of  the  epithelium  (after  Surface). 
J3.  Showing  the  type  of  gland  cells  of  the  funnel  region. 

C.  Transverse  section  through  the  wall  of  the  uterus  showing  the  deep  folds. 

D.  Section  from    the  albumin- secreting    portion  showing  the  opening  of  a 
tubular  gland  and  also  showing  the  character  of  the  cells. 

inner  circular.  At  places  in  this  portion  the  inner  bundles  may 
be  noted  to  extend  longitudinally.  In  embryological  development 
the  epithelial  layer  has  an  origin  different  from  the  outer  layers  of 
the  oviduct.  In  the  fetal  development  the  Miillerian  duct  arises 
as  a  thickening  along  the  Wolffian  body  just  ventral  to  the  gonad. 
This  Miillerian  duct  is  at  first  a  solid  cord  of  cells.  It  later  develops 
a  lumen,  and  grows  posteriorly  until  it  connects  with  the  cloaca. 
At  the  time  of  this  posterior  growth,  mesenchyme  cells  migrate 
in  from  the  surrounding  tissue  and  form  a  layer  about  the  duct. 
From  this  layer  of  mesenchyme  cells  there  are  developed  the  outer 


THE    URO-GENITAL    SYSTEM 


layers  of   the  oviduct,  which   layers   later  develop  the  muscular 
structure    and    the    connective    tissue.     The    epithelium    and   its 
derivatives,  which  represent  the  glandular  structures,  are  formed^ 
from  the  walls  of  the  old  Mlillerian  duct.     Thus  the  two  sets  of 
tissues,  having  different  origins,  likewise  have  different  functions. 
The  epithelium  is  concerned  entirely  with  secretion,  and  the  deriva- 
tives of  the  mesenchyme   are   con- 
cerned with  supporting  and  muscu- 
lar function.     «• 

To  summarize,  six  layers  of  tissue 
occur  in  the  funnel  region,  namely, 
an  outer  serous  covering,  an  outer 
longitudinal  muscular  layer,  a  layer 
of  connective  tissue,  an  inner  circular 
layer,  a  second  layer  of  connective 
tissue,  and  an  inner  mucous  layer. 
The  mucous  layer  is  made  up  of 
glands,  as  follows.  The  unicellular 
glands  occur  between  the  ciliated 
cells  of  the  epithelium.  These  glands 
are  found  only  in  the  posterior  half 
of  this  division  of  the  oviduct.  The 
glandular  grooves  are  made  up  of  an 
accumulation  of  gland  cells  at  the 
bottom  of  the  grooves  between  the 
secondary  folds  of  the  epithelium. 
These  are  found  in  all  parts  of  this 
division  except  the  extreme  posterior 
part.  In  the  posterior  part  we  find 
the  third  type  of  glands,  the  tubular 
variety. 

The  second  division  of  the  oviduct, 
as  stated  above,  is  the  albumin-secreting  portion.  The  funnel  divi- 
sion gradually  merges  into  the  second  portion.  These  two  portions 
are  distinguishable  from  each  other.  The  walls  of  the  albumin- 
secreting  portion  are  much  thicker  and  the  longitudinal  ridges  are 
higher.  This  section  is  the  longest  of  the  five  divisions,  measuring 
from  40  to  42  centimeters  in  length,  or  more  than  half  the  length 
of  the  oviduct.  The  albumin  division  terminates  rather  abruptly 
into  the  third  division,  the  isthmus  (Fig.  59,  A). 


FIG.  60,  A. — The  mucous  lining  of 
the  oviduct. 

E.  Section     of    the    epithelium 
from  the  vagina  showing  unicellular 
glands. 

F.  A  section  from  the  isthmus 
showing  opening  of  a  tubule. 


1 86  ANATOMY   OF   THE  DOMESTIC   FOWL 

It  is  probable  that  the  secretion  of  albumin  is  not  confined  to  the 
cells  of  the  second  division;  yet  we  are  safe  in  saying  that  the  major 
portion  is  formed  here.  The  folds  of  mucous  membrane  in  this  di- 
vision are  thicker  and  higher  than  in  the  funnel,  due  to  their  con- 
taining cells  of  the  high  columnar  type,  and  to  the  fuller  development 
of  the  glands  which  are  of  the  tubular  variety.  The  muscular  layer 
is  heavier,  and  therefore  the  muscular  power  to  force  along  the 
tubes'  contents  is  greater.  In  the  formation  of  the  mucous  folds  we 
find,  in  transverse  sections,  that  the  central  core  is  made  up  of  con- 
nective tissue  which  carries  blood-vessels  and  nerve  filaments,  as 
in  other  similar  glandular  structure.  The  epithelium  contains  glan- 
dular cells  of  two  varieties,  namely,  the  ciliated,  columnar  variety, 
and  the  unicellular,  goblet  variety  (Fig.  36,  No.  B,  2).  These  two 
kinds  of  glandular  cells  are  rather  evenly  distributed  throughout  the 
epithelium  of  this  section  of  the  oviduct.  The  unicellular  gland  cells 
are  more  numerous  at  the  mouths  of  the  ducts  leading  from  the  tu- 
bular glands.  The  nuclei  of  the  ciliated  cells  are  oval  and  lie  near 
the  middle  of  the  cells  or  a  trifle  toward  the  base  from  the  middle. 
The  protoplasm  of  the  cells  is  finely  granular.  Strong  cilia  in  con- 
siderable number  surmount  each  cell.  In  some  cases  the  goblet  or 
mucous  cells  have  pushed  apart  the  ciliated  cells,  and  their  prolon- 
gations extend  farther  than  the  surface  of  the  ciliated  cells.  The 
nuclei  of  the  goblet  cells  are  round,  and  lie  nearer  the  proximal 
end  than  those  of  the  ciliated  cells. 

The  third  division  of  the  oviduct,  the  isthmus,  continues  from  the 
albumin-secreting  portion  and  terminates  in  the  expanded  portion 
called  by  some  anatomists,  the  uterus.  Toward  the  posterior 
end  of  the  albumin-secreting  portion  the  longitudinal  folds  of  mu- 
cous membrane  become  lower,  making,  at  the  juncture  of  this  and 
the  isthmus,  a  clear  line  of  demarcation.  For  a  distance  of  2 
or  3  centimeters  the  folds  are  low,  after  which  they  gradually 
become  higher,  but  never  reach  the  height  or  thickness  of  those  in 
the  albumin-secreting  portion. 

The  clear-cut  line  between  the  albumin-secreting  portion  and 
the  isthmus  is  partly  due  to  a  zone  in  which  the  long  tubular  glands 
are  lacking.  The  core  of  the  folds  of  mucous  membrane  in  this 
zone  contain  much  more  connective  tissue.  The  cells  are  both 
ciliated  and  unicellular.  The  rest  of  the  histological  structure  of 
the  isthmus  is  the  same  as  that  of  the  albumin-secreting  portion. 


THE  TIRO-GENITAL   SYSTEM  187 

The  function  of  the  isthmus  is  to  secrete,  or  to  form,  the  shell 
membrane,  the  membrana  testacea. 

The  fourth  division  of  the  oviduct  is  the  uterus,  or  the  shell-gland 
portion  (Fig.  60,  C).  There  is  no  clear  line  of  demarcation  between 
the  isthmus  and  shell-gland  portion,  the  walls  gradually  expanding. 
In  this  region  the  folds  of  mucous  membrane  become  leaf-like  and  of 
considerable  length,  extending  into  the  lumen,  thus  affording  a 
greater  cellular  surface.  The  same  coats  of  the  duct  are  present 
here  as  in  other  parts;  but  the  outer  longitudinal  muscular  layer  is 
thicker  and  possesses  more  strength.  The  quantity  of  connective 
tissue  is  about  the  same.  The  glands  are  of  a  tubular  type  and  the 
same  two  varieties  of  epithelial  cells  are  found  here  as  elsewhere, 
namely,  the  ciliated  high  columnar  and  the  unicellular  mucous 
variety. 

In  the  active  glandular  cells  of  the  shell-forming  region  the  nuclei 
are  small,  dark  staining,  and  lie  toward  the  center  of  the  cell.  The 
chromatin  granules  and  nucleoli  take  on  a  comparatively  deep  basic 
stain,  but  they  do  not  show  the  intense  stain  found  in  the  albumin 
and  the  isthmus  region.  The  cytoplasm  of  the  uterine  tubular 
glands  does  not  present  as  heavy  a  granular  appearance  as  that  of 
the  albumin  portion.  These  cells  are  diffusely  granular,  the  granules 
appearing  of  one  size  and  taking  the  stain  faintly.  The  function 
of  this  portion  is  to  secrete,  or  form,  the  hard  calcareous  covering 
which  has  been  described  at  the  beginning  of  this  section. 

The  fifth  division  of  the  oviduct  is  the  vagina.  There  is  located, 
at  the  juncture  of  the  shell-gland  portion  with  the  vagina,  a  strong 
sphincter  muscle.  The  vagina  is  that  constricted  portion  of  the 
oviduct  extending  from  this  muscle  to  the  cloaca.  The  mucous 
membrane  forms  low  narrow  folds  with  secondary  folds,  which 
appear  continuous  with  those  of  the  shell-gland  portion.  The  core 
of  these  folds  is  composed  of  connective  tissue.  The  vagina  in 
the  hen  of  average  size  measures  from  12  to  13  centimeters  long 
(Surface).  The  inner  or  circular  muscular  layer  is  well  developed; 
it  is  much  thicker  than  in  any  other  part  of  the  oviduct.  This 
extra  development  gives  the  power  necessary  to  successfully  expel 
the  egg.  The  outer  longitudinal  layer  is  not  so  well  developed;  its 
bundles  are  scattered  throughout  the  connective-tissue  layers.  The 
egg  is  caused  to  move  along  in  the  oviduct  by  a  successive  series  of 
contractions  of  the  circular  muscular  fibers  posterior  to  it.  There 
are  no  tubular  glands  in  this  portion,  but  a  simple  layer  of  high 


1 88  ANATOMY   OF   THE   DOMESTIC   FOWL 

ciliated  columnar  epithelium,  and  some  goblet,  or  mucous  cells. 
The  cells  on  the  surface  generally  are  long  and  slender;  in  the  grooves 
between  the  mucous  folds  the  cells  are  shortest,  reaching  their 
greatest  length  at  the  tops  of  the  folds. 

The  function  of  the  vagina  is  the  secretion,  or  formation,  of  the 
outer  shell  cuticle  commonly  called  the  bloom,  and  also  in  certain 
breeds,  as  indicated  above,  the  tint. 

The  cloaca  furnishes  a  passage  way  from  the  vagina  to  the  ex- 
ternal world  by  way  of  the  anus.  The  walls  of  the  cloaca  contain 
glands. 

The  Ligaments  of  the  Oviduct. — It  is  held  in  position  by  two 
ligaments,  one  dorsal  and  one  ventral.  The  dorsal  ligament  of  the 
oviduct  is  formed  by  a  double  layer  of  peritoneum  with  a  very 
small  amount  of  connective  tissue  interposed.  The  peritoneum  is 
also  reflected  over  the  oviduct.  The  ventral  ligament  of  the  ovi- 
duct is  narrower  than  the  dorsal,  but  is  similarly  constructed.  Both 
ligaments  are  rather  veil-like  in  appearance.  During  the  first  four 
or  five  months  of  the  growth  of  the  young  female  fowl  the  develop- 
ment of  the  oviduct  and  its  ligaments  is  in  proportion  to  that  of  the 
body.  With  the  elongation  that  takes  place  about  the  time  of  func- 
tionation,  as  described  above,  the  ligaments  enlarge  in  proportion 
to  the  enlargements  of  the  oviduct.  The  dorsal  ligament  maintains 
a  line  of  attachment  to  the  body  wall  from  the  caudal  end  of  the  body 
cavity  to  the  fourth  thoracic  rib.  The  ventral  ligament  elongates 
only  slightly  during  this  developing  period.  It  becomes  thicker 
and  stronger  and  early  develops  a  muscular  coat.  It  also  grows  in 
width  except  at  the  caudal  end.  At  this  point  the  ligament  is 
simply  a  mass  of  muscular  tissue  of  the  smooth  or  involuntary  type. 
These  ligaments  are  fan-shaped. 

The  muscle  fibers  of  the  dorsal  ligament  of  the  laying  hen,  have 
their  origin  in  a  line  near  the  medial  side  of  the  dorsal  margin.  At 
this  point  the  bundles  of  fibers  are  quite  thick,  but  are  spread  out 
thinly  toward  the  margin  of  the  oviduct.  Frequent  anastomoses  are 
noted.  The  muscular  fibers  become  continuous  with  the  circular 
ones  of  the  oviduct. 

The  ventral  ligament  of  the  oviduct  of  the  laying  hen  is  largely  a 
muscular  cord  3  to  6  centimeters  in  diameter.  The  caudal  end 
is  thicker,  becoming  gradually  thinner  toward  the  anterior  portion. 
The  bundles  of  muscular  fibers  extend  toward  the  oviduct  blending 
with  the  circular  fibers  of  that  viscus.  The  ligaments  terminate 


THE   URO-GENITAL    SYSTEM  189 

anteriorly  in  such  a  manner  that  they  aid  in  forming  the  serous 
ovarian  pocket,  which  guides  the  yolk  into  the  fimbriated  portion, 
or  funnel,  of  the  oviduct.  The  walls  of  the  ovarian  pocket_are 
formed  by  the  left  abdominal  air-sac,  a  part  of  the  intestine,  and 
the  mesentery.  The  dorsal  portion  is  formed  by  the  roof  of  the 
abdominal  cavity,  and  the  ventral  portion  is  formed  by  the  dorsal 
wall  of  the  air-sac.  The  medial,  the  anterior,  and  the  lateral  limit 
of  the  pocket  are  formed  by  a  fusion  of  the  wall  of  the  air-sac  to 
the  mesentery  and  to  the  body  wall.  Posteriorly,  the  wall  consists 
of  the  transverse  part  of  the  small  intestine  and  the  caudal  portion 
of  the  left  caecum  with  their  attached  mesentery. 


THE  DUCTLESS  GLANDS 

These  glands  do  not  possess  excretory  ducts.  They  furnish 
materials  which  are  added  to  the  blood  or  lymph  as  it  passes  through 
them.  The  material  from  each  gland  is  known  as  an  internal  se- 
cretion, or  hormone.  Some  of  these  secretions  are  powerful  ma- 
terials and  influence  profoundly  the  body  nutrition.  The  ductless 
glands  are  usually  given  as  follows:  the  spleen,  the  lymph  glands, 
the  pineal  gland,  the  pituitary  body,  the  thyroid  gland,  the  thymus 
gland,  the  adrenal  glands,  and  the  parathyroids.  The  spleen,  the 
pituitary,  the  pineal,  and  the  lymph  glands  are  described  in  other 
sections. 

The  Thyroid  Gland  (Fig.  21,  No.  16).  Location. — The  thyroid 
gland  lies  on  the  ventral  side  of  the  carotis  communis  at  a  point 
where  the  carotis  communis  touches  the  jugular  vein,  which  is  about 
the  point  of  origin  of  the  vertebral  artery. 

Shape. — The  thyroid  gland  is  small,  oval  or  somewhat  roundish, 
and  red  or  rose-colored. 

Structure. — The  thyroid  gland  has  a  fibrous  capsule,  which  sends 
into  the  interior  septa  which  divide  it  into  acini.  These  acini  are 
closed  and  contain  a  fluid.  The  thyroid  is  a  ductless  gland.  Short 
arteries  from  the  carotis  enter  this  gland,  and  some  large  veins  con- 
nect it  with  the  jugular  vein.  The  lymph  vessels  which  lie  along  the 
neck  are  closely  connected  with  it  and  receive  twigs  from  the  gland. 
The  minute  lymphatic  capillary  endings  are  found  in  its  septa  and  in 
its  capsule.  The  acini  are  lined  with  a  single  or  a  double  row  of 
cuboidal  secreting  cells.  There  are  two  kinds  of  cells,  namely, 
secreting  and  resting  cells.  The  actively  secreting  cells  secrete 
colloid. 

The  parathyroids  consist  of  two  small  bodies  attached  to  the 
lower  pole  of  the  thyroid. 

The  Thymus  Gland  (Fig.  47,  No.  10).— The  thymus  gland  is  an 
organ  of  fetal  and  early  baby  chickhood.  It  soon  undergoes  retro- 
gressive changes  into  fat  and  connective  tissue.  It  is  of  epithelial 

190 


THE  DUCTLESS   GLANDS  IQI 

origin,  being  formed  in  fetal  life  from  the  entodermal  cells  of  the  dor- 
sal end  of  the  throat  fissure. 

Location. — The  thymus  gland  lies  anterior  to  the  thyroid,  the 
latter  lying  the  deeper. 

Shape. — The  thyroid  consists  of  two  lobes,  which  are  united  by 
connective  tissue,  and  appears  as  a  loop-like  acinous  gland  lying 
along  the  neck  and  near  the  region  of  the  bronchi  and  the  jugular 
veins  with  fibrous  extensions  toward  the  head. 

Structure. — The  gland  lobes  are  divided  into  lobules,  which  con- 
sist of  a  cortical  and  a  medullary  portion.  The  cortex  consists 
of  nodules  of  compact  lymphatic  tissue  similar  to  those  found  in  the 
lymph  glands.  These  occupy  the  chambers  formed  by  the  septa 
of  connective  tissue.  In  the  medulla  there  are  a  number  of  spherical, 
or  oval  bodies  composed  of  concentrically  arranged  epithelial  cells. 
These  are  known  as  Hassall's  corpuscles,  and  represent  only  the 
remains  of  the  original  glandular  epithelium.  They  are  charac- 
teristic of  the  thymus  gland.  The  thymus  appears  to  be  a  type  of 
lymph  organ.  Lymph  vessels  are  rare;  a  few  blood-vessels  on  the 
upper  side  form  capillary  nets. 

The  Adrenal  Gland  (Fig.  54,  F).  Location. — The  adrenal  gland, 
often  called  the  supra-renal  capsule,  lies  just  anterior  to  the  front 
part  of  the  anterior  lobe  of  the  kidney,  adjacent  to  the  testicles  in 
the  male  and  to  the  ovary  in  the  female.  It  is  loosely  attached  by 
connective  tissue  to  the  posterior  aorta  and  to  the  vena  cava. 

Shape. — It  is  yellowish-brown  or  reddish-pink  in  color,  small, 
and  of  irregular  formation. 

Structure. — The  adrenal  gland  consists  of  a -cortical  and  a  med- 
ullary portion,  although  these  two  parts  are  not  distinctly  marked. 
The  cortical  portion  has  columns  which  extend  deeply  into  the  gland, 
and  the  medullary  portion  sends  columns  into  the  cortical  portion. 
Therefore,  the  two  substances,  lying  side  by  side,  form  a  cord-like 
structure. 

It  is  probable  that  the  cortical  portion  is  derived  from  the  in- 
growths of  the  peritoneum,  and  the  medullary  cords  from  the  sym- 
pathetic ganglion. 

The  cells  are  cylindrical  or  polygonal  in  shape,  with  an  eccentric 
substance  between  the  columns.  The  cords,  or  columns,  form  be- 
tween them,  elongated  channels  which  extend  into  the  interior  of 
the  gland  and  end  as  blind  or  caecal  extremities.  Large  ganglionic 
nerve  cells  belonging  to  the  sympathetic  system  occur  near  the  sur- 


IQ2  ANATOMY   OF   THE   DOMESTIC   FOWL 

face  of  the  gland.  The  blood-vessels  are  not  well  developed  in  the 
interior  of  the  gland  but  are  numerous  and  of  good  size  in  the  outer 
parts.  Lymph  vessels  are  also  present. 

Function. — The  adrenals  are  ductless  glands.  They  secrete  an 
internal  secretion,  or  hormone,  which  influences  the  tonus  of  the 
blood-vessels.  An  extract  from  these  glands  is  called  adrenalin. 


THE  RESPIRATORY  APPARATUS  (Figs.  50  and  61,  A) 

Owen  says:  " Notwithstanding  the  extent  and  activities  of  the 
respiratory  function  in  birds,  the  organs  subservient  thereto  mani- 
fest more  of  a  reptilian  than  of  the  mammalian  type  of  formation." 

By  the  action  of  the  respiratory  organs  certain  chemical  and 
physical  changes  take  place  in  the  blood.  The  chief  of  these  con- 
sists in  absorption  of  oxygen  from,  and  giving  off  carbon  dioxid 
to,  the  atmospheric  air,  the  former  changes  being  necessary  for  the 
elaboration  of  the  fluid,  the  latter  for  the  elimination  of  a  substance 
which,  if  retained,  would  prove  injurious.  The  organs  of  respira- 
tion are  invariably  adapted  to  the  wants  of  the  animal  and  the  me- 
dium in  which  it  lives. 

In  the  bird,  which  breathes  through  its  nose,  the  organs  of  respi- 
ration are  nostrils,  nasal  chambers,  pharynx,  superior  larynx,  tra- 
chea, inferior  larynx,  bronchi,  bronchial  tubes,  lungs,  and  air-sacs. 

The  Nostrils  and  the  Nasal  Chambers. — The  nostrils  of  the  bird 
open  externally  by  two  small  elliptical  openings,  which  pierce  the 
upper  mandible.  Within  each  nasal  chamber  (Fig.  26,  A)  are  three 
turbinated  laminae,  or  turbinated  bones.  The  inferior  one  is  a  sim- 
ple fold  adhering  to  the  lower  and  anterior  part  of  the  nasal  septum. 
The  middle  turbinated  bone  is  the  largest.  It  is  of  infundibular 
form,  and  adheres  by  its  base  to  the  septum  and  externally  to  the 
side  wall  of  the  nose.  It  is  convoluted  with  two  and  a  half  turns. 
The  superior  bone,  of  bell  shape,  adheres  superiorly  to  the  frontal 
bone.  The  internal  turbinated  bone  extends  toward  the  orbit; 
the  external  terminates  in  a  cul-de-sac  behind  the  middle  turbinal 
(Fig.  26,  No.  A,  i  and  2,  and  G). 

The  nostrils  are  separated  by  a  partition  which  is  partly  bony  and 
partly  cartilaginous.  The  posterior  nares  is  represented  by  a  long 
slit  in  the  hard  palate. 

The  Pharynx  and  the  Superior  Larynx. — A  transverse  row  of 
horny,  filiform  papillae  marks  the  anterior  border  of  the  pharynx, 
where  in  other  animals  the  soft  palate,  or  velum,  is  located.  (For 
further  description  of  the  pharynx  see  special  chapter.) 

The  supero-posterior  border  of  the  larynx,  at  the  juncture  of  the 

13  193 


IQ4  ANATOMY   OF   THE   DOMESTIC  FOWL 

larynx  and  the  esophageal  margin,  is  marked  by  a  second  transverse 
row  of  horny,  filiform  papillae,  which  point  backward.  There  is 
no  epiglottis.  The  superior  part  of  the  larynx  is  pierced  by  an  oval, 
slit-like  opening,  the  glottis,  which  is  provided  with  two  lips.  These 
when  brought  together,  tightly  close  the  glottis  so  that  nothing  can 
fall  through  into  the  larynx  in  the  act  of  deglutition.  The  margin, 
or  rim,  of  this  opening  is  called  the  rami  glottis.  The  glottis  is  con- 
trolled by  two  pair  of  muscles. 

The  superior  surface  of  the  larynx  is  somewhat  triangular  with  the 
apex  directed  forward.  A  few  delicate,  filiform  papillae  are  upon 
its  surface.  The  bird  has,  as  already  indicated,  two  larynxes,  the 
superior  larynx  located  at  the  upper  end  of  the  trachea,  and  the 
inferior  larynx  at  the  bifurcation  of  the  trachea.  The  inner  sur- 
face of  the  superior  larynx  is  smooth  and  does  not  contain  vocal 
cords;  it  is  in  these  animals  simply  a  passage  for  air.  It  is  joined 
to  the  trachea  inferiorly  by  a  ligament,  the  crico-trachealis,  and  lies 
at  the  base  of  the  tongue  supported  by  two  cornua  of  the  os  hyoideum. 

The  cartilages  forming  the  principal  support  of  the  superior  larynx, 
consist  of  four  pieces,  as  follows:  one  unequal  ventral  piece,  two  side 
pieces,  and  one  unequal  dorsal  piece.  The  cartilaginous,  flat, 
ventral  cricoid,  early  in  the  bird's  life,  often  becomes  bony.  The 
side  pieces  are  separated  from  it,  only  exceptionally  fusing  with  it. 
The  dorsal  cricoid  piece  also  often  becomes  bony.  The  two  aryte- 
noid  cartilages,  joined  with  the  'cricoid  superiorly,  are  three-sided, 
and  are  united  to  each  other  in  a  sharp  angle.  They  form  the  su- 
perior opening  of  the  superior  larynx. 

The  Trachea. — The  trachea  is  cylindrical  and  varies  in  length  in 
different  kinds  of  birds  in  accordance  with  the  length  of  the  neck. 
It  consists  of  from  90  to  120  cartilaginous  rings,  complete  with  the 
exception  of  the  two  uppermost,  which  rings  are  held  together  by 
intercartilaginous  ligaments.  The  tracheal  rings  are  constructed 
of  hyaline  cartilage  and  the  ligaments  of  fibrous  tissue.  It  is  lined 
with  a  mucous  membrane  covered  by  columnar  epithelium.  The 
trachea  is  a  passage  for  air  alone  and  terminates  in  the  inferior 
larynx. 

The  Inferior  Larynx. — The  inferior  larynx,  called  the  true  larynx 
because  it  is  the  organ  of  voice,  is  located  at  the  inferior  end  of  the 
trachea  and  the  superior  ends  of  the  bronchi.  By  some  anatomists 
this  organ  has  been  called  the  larynx  broncho-trachealis.  The  larynx 
is  flattened  laterally  in  fowls.  It  contains  two  membranous  folds, 


THE    RESPIRATORY   APPARATUS  1 95 

which  in  the  production  of  sound  are  caused  to  vibrate.  These  folds 
are  half -moon  shaped  elastic  structures,  located  in  the  bony,  arrow-' 
like  way,  intero-inf  eriorly .  These  structures  are  called  the  membfuna 
tympana  interna.  In  the  duck  this  inferior  larynx  is  represented  by 
a  drum-like  cartilaginous  and  bony  structure,  called  the  bulla  tym- 
paniformis.  This  bulla  is  a  resonant  apparatus  which  serves  to 
strengthen  the  voice. 

In  song  birds  there  is  a  double  glottis,  usually  produced  by  a 
bony  bar,  called  the  pessulus,  or  os  transversale,  which  traverses  the 
lower  end  of  the  trachea  from  front  to  rear.  It  supports  a  thin 
membrane  which  ascends  into  the  tracheal  area,  and,  terminating 
there  by  a  free  concave  margin,  is  called  the  membrana  semi-lunaris. 
This  is  most  developed  in  singing  birds,  and  being  vibratile,  forms 
an  important  part  of  their  trilling  vocal  apparatus.  The  air  passes 
on  each  side  of  the  membrana  semi-lunaris  and  its  sustaining  bone  to 
and  from  the  bronchi  and  lungs. 

The  last  ring  of  the  trachea  usually  expands  as  it  descends,  with 
its  fore  and  posterior  parts  produced,  and  the  lower  lateral  borders 
concave;  the  extremities  of  the  pessulus,  butts  against  the  angle 
thus  formed  and  expands  to  be  attached,  also  with  the  fore  and  pos- 
terior terminations  of  the  first  half  ring  of  the  bronchus,  strength- 
ening and  clamping  together  the  upper  part  of  the  vocal  framework. 
The  second  bronchial  half  ring  is  flattened  and  curved  with  the  con- 
vexity outward,  like  the  first,  but  is  more  movable.  The  third 
half  ring  is  less  curved  and  further  separated  from  the  second,  to 
the  extremities  of  which  its  own  are  connected  by  a  ligament,  and, 
for  the  intervening  extent,  by  a  membrane;  its  inner  surface  supports 
the  fibrous  cord,  or  fold,  which  forms  the  outer  lip  of  the  glottis 
of  that  side;  it  is  capable  of  rotary  movements  on  its  axis,  aiicjl  is 
an  important  agent  in  the  modulation  of  the  voice.  All  these 
parts  just  described  are  bony. 

The  Bronchi  and  the  Lungs. — The  bronchi,  two  in  number, 
are  provided  with  only  incomplete  cartilaginous  rings.  They  enter 
the  inferior  face  of  the  lungs,  toward  their  anterior  and  middle 
thirds  and  break  up  into  primary  bronchi,  which  give  off  at  right 
angles,  secondary  bronchi,  and  these  latter  in  turn  give  off  tertiary 
branches. 

The  lungs  occupy  only  about  one-seventh  of  the  thoracic  space. 
They  are  long,  flattened,  and  oval,  extending  along  each  side  of  the 
spine  from  the  second  dorsal  vertebra  to  the  anterior  end  of  the  kid- 


ig6 


ANATOMY   OF   THE   DOMESTIC   FOWL 


neys,  and  laterally  to  the  juncture  of  the  vertebral  with  the  sternal 
portions  of  the  ribs.  They  present  two  faces,  a  superior  convex  and 
an  inferior  concave;  two  borders,  an  external  and  an  internal;  and  two 
extremities,  an  anterior  and  a  posterior  (Fig.  61).  The  convex  sur- 


FIG.  61. — The  lung. 

A.  The  outer  surface  of  one  lung.     Note  the  flattened  oval  shape.     It  is  not 
divided  into  lobes.      I,   The  bronchus.     2,   Primary  tubules  showing  openings 
leading  from  the  primary  tubules  to  the  secondary  tubules.     3,  Openings  of  two 
of  the  large  tubes  into  the  diaphragmatic  and  abdominal  air-sacs. 

B.  Sectioned  surface  of  lung,     i,   Secondary  tubules.     2,   Tertiary  tubules. 
3,  Interlacing  capillaries  and  air  cells. 

C.  i,  Cavity  of  tubule.     2,  Its  lining  membrane  supporting  blood-vessels  with 
large  areolae.     3,  Perforations  in  the  membrane  at  the  orifices  of  the  lobular 
passage.     4,  Interlobular  space  containing  the  terminal  branches  of  the  pulmo- 
nary vessels  supplying  the  capillary  plexus,  5,  5,  to  the  meshes  of  which  air  gets 
access  by  the  lobular  passage. 


face  is  also  called  the  dorsal,  costal,  or  superior  face.  It  is  moulded 
on  the  walls  of  the  thorax  and  occupies  a  part  of  the  intercostal 
space,  pushing  the  intercostal  muscles  outward.  When  the  surface 
of  the  lung  is  examined  it  is  seen  to  be  furrowed  where  the  ribs 
pressed  during  life.  These  furrows  are  as  deep  as  the  ribs  are 


THE   RESPIRATORY   APPARATUS  IQ7 

thick.     The  sides  of  the  lungs  are  covered  with  connective  tissue 
which  attaches  them  to  the  costal  walls. 

The  concave,  or  inferior,  face  also  called  the  diaphragmatic  or 
visceral  face  is  directed  downward.  The  diaphragm  separaTes~1t 
from  the  abdominal  viscera.  The  surface  is  covered  by  connective 
tissue  which  closely  attaches  it  to  the  diaphragm.  It  is  perforated 
by  the  five  tubules  which  bring  the  posterior  air-sac  into  communi- 
cation with  the  lungs. 

The  borders  of  the  lungs  extend  parallel  to  the  long  axis  of  the 
body.  The  internal  border  is  rectilinear,  thick,  and  rounded.  The 
external  border  is  convex,  thin,  and  sharp. 

The  anterior  extremity  terminates  in  a  sharp  point  which  occupies 
a  space  formed  by  the  ribs  externally  and  the  inferior  spines  inter- 
nally. The  posterior  extremity  is  somewhat  rounded  and  extends 
as  far  back  as  the  anterior  border  of  the  kidneys. 

As  soon  as  the  bronchi  enter  the  lungs  they  become  broadened, 
the  cartilaginous  rings  disappear,  and  they  continue  as  membranous 
channels  whose  diameters  gradually  decrease,  as  they  extend  back- 
ward, to  the  point  where  they  terminate  in  the  ostium  caudate,  at 
which  point  they  are  surrounded  by  a  cartilaginous  ring.  The 
ostium  caudale  brings  the  tubules  into  communication  with  the 
ventral  air-sacs. 

Twelve  air  tubules  have  their  origin  from  each  common  bronchus, 
or  trunk.  Four  are  given  off  from  the  internal  wall  of  the  main 
bronchus  by  a  series  of  openings  arranged  in  a  row.  Seven  are  given 
off  from  the  external  wall  by  a  second  series  similar  to  that  of  the 
first.  The  twelfth  extends  from  the  inferior  wall,  and  immediately 
takes  a  course  downward  and  outward  and  communicates  with  the 
posterior  diaphragmatic  air-sac.  This  may  be  considered  as  the 
terminal  branch  of  the  trunk. 

All  of  these  secondary  canals,  except  the  last,  pass  toward  the 
periphery  of  the  lung.  They  divide  and  subdivide  at  the  periphery, 
covering  it  with  their  ramifications.  The  canals  extending  from  the 
inner  wall  are  distributed  to  the  inferior  face  of  the  lung.  Those 
extending  from  the  outer  wall  are  distributed  to  the  outer  face  of  the 
lung.  The  first  constitute  the  diaphragmatic  and  the  second  the 
costal  bronchial  tubes. 

The  four  diaphragmatic  bronchial  tubes  are  numbered  in  the  order 
in  which  they  are  given  off.  The  first  is  carried  forward  horizontally, 
the  second  transversely  inward,  the  third  obliquely  inward  and  back- 


198  ANATOMY   OF   THE   DOMESTIC   FOWL 

ward,  and  the  fourth  directly  backward.  They  have,  by  some 
anatomists,  been  called  the  anterior,  the  internal,  and  the  pos- 
terior diaphragmatic  bronchial  tubes.  There  are  two  posterior 
diaphragmatic  bronchial  tubes;  the  larger  called  the  great  pos- 
terior, and  the  smaller,  which  passes  directly  backward,  the  small 
posterior. 

The  costal  bronchial  tubes,  seven  in  number,  are  numbered  from 
the  front  backward  in  the  order  they  are  given  off.  Parallel  at 
their  origin,  and  side  by  side,  like  pipes  of  an  organ,  they  soon  spread 
out  in  fan  shape  like  the  preceding.  They  extend  from  their  cen- 
tral origin  to  the  periphery.  The  first  extends  obliquely  upward 
and  inward  to  the  anterior  extremity  of  the  lung.  All  branches 
from  this  bronchus  extend  from  its  anterior  wall.  The  first  branches 
are  inflected  to  reach  the  external  border  of  the  lung.  The  succeed- 
ing branches  are  directed  forward  and  the  last  forward  and  inward. 
They  all  meet  those  from  the  anterior  diaphragmatic  bronchus, 
but  do  not  anastomose  with  them. 

The  second,  the  third,  .and  the  fourth  costal  bronchi  extend  in  a 
transverse  manner  and  ramify  on  the  inner  border  of  the  lung. 

The  fifth  and  the  sixth  are  directed  toward  the  posterior  extremity 
of  the  lung.  The  seventh,  very  small,  reaches  this  extremity,  where 
it  disappears. 

The  first  costal  bronchus  is  the  largest;  those  following  it  gradually 
become  smaller.  At  their  points  of  origin  they  adhere  closely  to 
the  ribs.  They  are  all  imperforate,  which  is  a  distinguishing  fea- 
ture from  those  occupying  the  opposite  face. 

The  canaliculi  or  tertiary  tubules  given  off  by  these  secondary 
bronchial  tubes  do  not  differ  greatly  in  caliber  in  the  various  parts. 
They  are  given  off  at  right  angles  from  the  pulmonary  wall  of  each 
bronchus,  and  extend  perpendicularly  into  the  lung  substance. 
Thus  we  find  three  kinds  of  conduits,  the  primary,  the  secondary, 
and  the  peripheral,  or  tertiary.  The  first  are  like  the  barbs  of  a 
feather  on  its  shaft;  and  the  second,  and  parenchyma tous  are  im- 
planted on  the  pulmonary  walls  of  the  first,  like  the  hairs  of  a 
brush  on  their  common  base.  Thus  instead  of  the  branching  of 
the  bronchi  being  dichrotomous,  as  in  mammals,  it  is  piniform. 

The  canaliculi,  or  finer  tubules,  communicate  with  one  another. 
The  inner  microscopic  appearance  of  the  canaliculi  indicate  that 
they  are  divided  into  areola,  which  gives  them  a  cellular  aspect 
These  tertiary  bronchi  open  on  a  dense  labyrinth  of  blood  capillaries 


THE   RESPIRATORY  APPARATUS  199 

(Fig.  61,  C).  At  this  point  the  ciliated  epithelial  cells  give  way  to 
simple  squamous  epithelium. 

Thus  we  find  three  kinds  of  bronchi,  or  their  ramifications,  as 
follows:  the  primary,  the  secondary,  and  the  tertiary. 

The  Air-sacs  (Fig.  6 1 ,  A ) . — The  air-sacs  are  bladder-like  structures 
consisting  of  a  delicate  cellulo-serous  membrane,  an  extension  from 
the  bronchial  tubes,  in  some  places  strengthened  by  an  external 
envelope  of  elastic  fibrous  tissue.  Long  thin  blood-vessels  are  dis- 


6 

FIG.  61,  A. — Diagram  of  air-sacs  and  their  location,  i,  The  proximal  end  of  the 
humerus.  2,  The  proximal  end  of  the  right  clavicle.  3,  The  cervical  air  cell. 
4,  The  right  coracoid  bone.  5,  The  anterior  thoracic  air  cell.  6,  The  right  side 
of  the  sternum.  7,  The  right  side  of  the  liver.  8,  The  peritoneum.  9,  The 
right  abdominal  air  cell.  10,  The  coccyx,  n,  The  proximal  end  of  the  right 
femur.  12,  The  right  supero-posterior  air-sac.  13,  The  right  infero-posterior 
air-sac.  14,  The  right  lung.  15,  The  axillary  extension  of  the  air-sac.  16,  The 
obturator  foramen,  17.  The  pelvis. 

tributed  in  the  substance  of  these  walls.  They  are  branches  from 
vessels  of  the  general  circulation  and  not  extensions  from  those  of 
the  lungs.  No  lymphatics  have  been  found  in  the  air-sacs. 

These  sacs  do  not  communicate  with  each  other  and  normally 
they  are  not  fully  inflated.  In  some  locations  they  extend  into  the 
bones  and  are  in  communication  with  the  extensions  of  the  bronchial 
tubes.  In  fact,  by  some  anatomists  they  have  been  called  "  bladder- 
like,  extra-pulmonary  expansions  of  the  bronchial  tubes,  free  from 
cartilage."  The  air-sacs  make  the  bird's  body  lighter,  thus  making 


200  ANATOMY    OF    THE   DOMESTIC   FOWL 

long-continued  flight  possible.  They  are  best  developed  in  those 
birds  which  fly  most.  There  are  four  pairs  of  cells  and  one  single 
cell  from  which  all  other  expansions  and  extensions  are  made. 
These  sacs  are  as  follows:  a  single  anterior  thoracic,  and,  in  pairs, 
cervical,  anterior  diaphragmatic,  posterior  diaphragmatic,  and 
abdominal. 

The  Anterior  Thoracic  Air-sac. — The  anterior  thoracic  air-sac  is 
located  above  the  clavicles  and  the  interclavicular  space,  in  the 
cavity  of  the  thorax.  It  is  related  superiorly  with  the  trachea  and 
the  esophagus;  laterally  with  the  lungs  and  the  cervical  air-sacs; 
inferiorly  with  the  sternum,  the  clavicle,  and  the  interclavicular 
aponeurosis;  posteriorly  with  the  heart  and  the  anterior  diaphrag- 
matic reservoir;  and  anteriorly  with  the  integuments  of  the  neck. 
It  contains  the  inferior  larynx  and  the  two  primary  bronchi,  and 
large  vascular  trunks  from  which  are  given  off  vessels  supplying  the 
neck  and  the  wings. 

Three  prolongations,  called  subpectoral,  subscapular,  and  middle, 
or  humeral,  arise  from  the  lateral  walls  of  this  air-sac.  These 
prolongations  cross  the  walls  of  the  thorax  and  pass  around  the 
articulation  of  the  shoulder. 

The  subpectoral  prolongation  extends  from  the  thoracic  reservoir 
by  an  orifice  situated  behind  the  coracoid,  and  passes  beneath  the 
tendon  of  the  great  pectoral  muscle.  When  the  pectoralis  major 
contracts,  this  contraction  dilates  the  subjacent  cell  and  draws  into 
it  a  greater  quantity  of  air. 

The  subscapular  and  the  humeral  prolongations  communicate  with 
the  thoracic  air  cell  by  a  common  opening  situated  behind  the  small 
adductor  muscle  of  the  humerus.  The  subscapular  prolongation, 
after  leaving  this  point,  spreads  under  the  scapular  and  the  sub- 
scapular  muscle,  which  it  separates  from  the  ribs  and  corresponding 
intercostal  muscles,  and  extends  in  a  longitudinal  direction. 

The  humeral  prolongation,  smaller  than  the  subscapular,  occupies 
the  axilla,  and  is  in  shape  triangular.  It  has  from  its  summit  into 
an  infundibular  fossa,  an  extension  which  enters  the  canal  of  the 
humerus.  The  walls  of  this  cell  form  the  lining  of  the  air  space  in 
the  humerus. 

The  thoracic  air-sac  thus  possesses  numerous  membranous  folds 
which  divide  its  cavity.  The  contiguous  structures  which  it  over- 
lies, as  the  trachea,  the  esophagus,  the  muscles  of  the  inferior  larynx, 
as  well  as  the  arteries  and  veins,  make  its  outer  walls  irregular. 


THE   RESPIRATORY  APPARATUS  2OI 

The  thoracic  air-sac  communicates  with  the  lungs  through  an 
infundibular  opening  located  on  the  external  side  of  each  bronchus. 
This  orifice  is  dilated  during  inspiration,  by  the  contraction  oLthe 
two  first  fasciculi  of  the  diaphragm. 

The  Cervical  Air-sacs. — The  two  cervical  air-sacs  are  located  just 
above  the  thoracic  air-sac  at  the  inferior  part  of  the  neck  and  in 
front  of  the  lungs.  They  are  cone-shaped  with  the  base  directed 
forward  and  the  apex  backward.  They  are  related  superiorly  with 
the  cervical  muscles,  and  inferiorly  with  the  thoracic  air-sac  from 
which  they  are  separated  by  the  trachea,  the  esophagus,  the  pneu- 
mogastric  nerve,  and  the  jugular  veins.  The  walls  touch  each 
other  internally,  and  form  a  median  septum  which  includes  in 
its  substance  the  two  common  carotid  arteries.  Externally  they 
are  related  to  the  origin  of  the  cervical  nerves,  to  each  of  which  they 
contribute  a  small  sheath.  They  surround  the  vertebral  artery, 
and  are  connected  with  the  subcutaneous  muscles  and  the  skin. 
The  summits  communicate  with  the  anterior  diaphragmatic  bron- 
chus. Prolongations  extend  from  their  bases  which  conduct  the  air 
into  all  the  vertebrae  of  the  neck  and  the  back,  into  all  the  vertebral 
ribs,  and  into  the  spinal  canal.  Parallel  with  and  adjacent  to  the 
vertebral  arteries,  and  lodged  in  the  canals  excavated  in  the  trans- 
verse processes  of  the  cervical  vertebrae,  are  two  cervical  prolonga- 
tions, one  on  each  side,  which  extend  to  the  cranium  from  the  base 
of  the  cervical  reservoirs.  From  their  sides,  at  the  last  six  cervical 
vertebrae,  are  six  extensions  in  the  form  of  diverticuli,  which, 
lying  against  each  other,  pass  from  each  side  into  the  muscles  of  the 
neck.  They  are  surrounded  by  a  thin  fibrous  envelope,  a  continua- 
tion of  the  mucous  lining  of  the  sac,  and  apparently  form  a  canal  in 
the  inferior  part  of  this  region.  These  prolongations  are  better 
developed  in  palmipedes  than  in  chickens.  On  the  internal  side 
of  these  prolongations,  one  or  more  foramina  penetrate  the  vertebral 
segment,  which  allow  the  extensions  of  the  prolongations  into  the 
spinal  canal.  Chauveau  states  that  "as  the  medullary  tissue  is 
replaced  by  air  in  the  bones  of  birds,  so  is  the  subarachnoid  fluid 
replaced  by  air  around  the  spinal  cord." 

The  prolongations  extending  from  the  cervical  air-sacs,  having 
entered  the  thorax,  terminate  by  passing  into  the  first  dorsal  verte- 
bra. After  permeating  every  part  of  this  vertebra,  it  escapes  by  a 
lateral  opening  and  forms  a  small  sac  located  between  the  first  two 
ribs,  near  the  origin  of  the  first  dorsal  nerve.  From  this  sac  an 


202  ANATOMY   OF   THE   DOMESTIC   FOWL 

extension  is  given  off,  which  enters  the  second  vertebral  segment  at 
the  antero-lateral  part;  from  this  point  it  passes  back,  forming  a 
new  air-sac  between  the  second  and  third  ribs.  It  now  passes  in 
the  same  manner  into  the  third  vertebra  and  extends  through  the 
third  intercostal  sac,  and  so  on  till  the  last  dorsal  vertebra  has  been 
served.  At  the  same  time  that  these  sacs  receive  the  air  from  the 
vertebrae  preceding  them,  and  transmit  it  to  those  which  follow, 
they  communicate  it  to  all  the  vertebral  ribs.  The  aerial  currents 
which  leave  the  cervical  air-sacs  do  not  communicate  with  those 
of  the  cranium.  Experiments  show  that  the  cranial  bones  have 
apparently  no  communication  with  the  respiratory  apparatus. 

The  Anterior  Diaphragmatic  Air -sac. — The  two  anterior  dia- 
phragmatic or  supero-posterior  air-sacs  are  related  with  the  lungs 
anteriorly,  and  with  the  abdominal  viscera  posteriorly.  Anteriorly 
also  is  the  thoracic  air-sac,  posteriorly  are  the  posterior  diaphrag- 
matic air-sacs,  and  laterally  the  ribs  and  the  intercostal  muscles 
and  internally  is  the  esophagus.  The  lungs  communicate  with  these 
air-sacs  through  circular  openings  from  the  great  posterior  diaphrag- 
matic bronchus  and  frequently  by  a  second  opening  from  this  same 
tube.  These  are  the  only  sacs  which  receive  air  from  the  lungs 
through  two  openings. 

The  Posterior  Diaphragmatic  Air-sac. — The  two  posterior  dia- 
phragmatic, or  infero-posterior  air-sacs  are  oval  in  shape  and  located 
between  the  thoracic  and  the  abdominal  cavity.  They  are  related 
anteriorly  with  the  anterior  diaphragmatic  air-sacs.  These  two 
sacs  form  a  vertical  transverse  partition.  The  posterior  diaphrag- 
matic air-sacs  are  related  posteriorly  with  the  abdominal  air-sacs 
from  which  they  are  separated  by  the  diaphragm.  They  are 
related  below  with  the  lateral  parts  of  the  sternum  and  the  sternal 
ribs,  and  externally  with  the  ribs  and  the  intercostal  muscles. 
These  air-sacs  communicate  with  the  lungs  through  openings  located 
in  the  middle  part  of  the  external  border  of  the  lung,  into  the 
extremity  of  voluminous  bronchial  tubes  which  follow  the  direction 
of  the  largest  air  tubes. 

The  Abdominal  Air-sacs. — The  two  abdominal  air-sacs  located 
on  each  side  of  the  abdominal  cavity,  when  inflated  with  air,  form 
enormous  bladder-like  structures.  They  are  related  laterally  with 
the  abdominal  wall  and  internally  with  the  abdominal  viscera.  The 
anterior  extremities  are  in  communication  with  the  mesobronchi 
and  are  somewhat  inflected  to  pass  under  the  fibrous  arches  extend- 


THE  RESPIRATORY  APPARATUS  203 

ing  from  the  spine  to  the  pelvis.  Anteriorly  these  sacs  adjoin  the 
diaphragm,  the  testes  in  the  male,  and  ovary  in  the  female,  and  to 
the  parietes  of  the  abdomen  and  those  of  the  pelvis.  Below  and  in 
front,  they  rest  on  a  fibrous  septum,  which  in  all  birds  divides  the 
abdominal  cavity  into  two  smaller  cavities:  one  anterior,  represent- 
ing the  abdomen  and  containing  the  liver;  the  other  posterior, 
representing  the  pelvis  and  containing  the  gizzard  and  the  intestines. 
The  anterior  portion  overlies  the  posterior  part  of  the  lobes'  of  the 
liver,  the  proventriculus,  the  spleen,  and  the  gizzard.  The  kidneys 
are  located  above  these  air-sacs.  Dorsal  to  the  sacs  is  also  a  part  of 
the  intestines  and  in  the  female  the  oviduct.  The  abdominal  air- 
sacs  are  attached  by  a  ligament-like  structure  in  their  medial,  their 
anterior,  and  their  lateral  margin.  The  posterior,  the  dorsal,  and 
the  ventral  margin  are  free.  Mesially  this  attachment  is  to  the 
mesentery,  connecting  the  left  caecum  to  the  dorsal  margin  of  the 
gizzard,  and  also  to  the  mesentery  of  the  proventriculus.  The 
anterior  attachment  is  to  the  body  wall  and  extends  in  front  of  the 
end  of  the  ovary  and  the  adrenal  glands.  At  the  antero-lateral  part 
of  the  body  cavity  the  attachment  extends  in  a  widening  band  along 
the  lateral  side  of  the  ovary  and  of  the  oviduct,  as  far  back  as  the 
caudal  margin  of  the  sac.  The  lateral  attachment  is  related  to 
the  kidney,  the  dorsal  ligament  of  the  oviduct,  and  the  abdominal 
wall. 

Each  of  these  abdominal  sacs  has  three  extensions:  one  supra- 
renal and  two  femoral. 

The  suprarenal  extension  leaves  the  principal  sac  at  the  postero- 
external  part  of  the  kidney,  extends  upward,  and  forward,  and 
expands  over  the  surface  of  the  kidney.  At  the  internal  border  of 
the  kidney,  this  prolongation  extends  between  the  transverse 
processes  of  the  sacral  vertebrae,  reaches  a  height  of  the  first  dorsal 
vertebra,  forms  a  triangular  canal  located  above  the  sacrum  in 
the  sacral  channel,  and  is  separated  from  its  fellow  by  a  series  of 
corresponding  spinous  processes. 

The  two  femoral  extensions,  an  anterior,  small,  and  a  posterior, 
large,  extend  from  the  abdominal  air-sac  at  the  cotyloid  cavity,  leave 
the  pelvis  through  the  bony  passage  occupied  by  the  crural  vessels, 
extend  around  the  coxo-femoral  articulation,  and  terminate  in  a 
blind  extremity.  In  some  birds,  particularly  in  birds  of  prey  and 
ostriches,  there  are  prolongations  extending  into  the  femur,  entering 
through  a  foramen  at  the  anterior  part  of  the  great  trochanter. 


204  ANATOMY   OF   THE   DOMESTIC   FOWL 

Summary  of  Bones  Supplied  by  Each  Air-sac. — The  thoracic  air- 
sac  communicates  on  each  side  of  the  thorax  with  twelve  bones, 
including  the  four  sternal  ribs.  It  supplies  air  to  the  clavicles,  which 
are  perforated  at  both  their  extremities,  and  to  the  coracoids,  which 
are  perforated  just  below  their  scapular  extremity.  The  sternum 
is  supplied  through  two  series  of  openings,  the  middle  ones  that 
conduct  air  into  the  sternal  ridge  and  the  lateral  ones,  eight  in 
number  and  very  small,  correspond  to  the  intercostal  spaces.  The 
sternal  ribs  are  penetrated  by  small  foramina  at  their  inferior  ex- 
tremities. From  the  subscapular  extension  the  scapulae  receive  air 
through  one  or  two  foramina  at  their  anterior  extremity.  The 
humeral  prolongation  supplies  the  humerus  through  a  foramen 
located  at  the  upper  edge  of  the  humeral  fossa,  at  the  infero-internal 
part  of  the  articular  head. 

The  cervical  air-sac  furnishes  air  to  all  the  cervical  vertebrae,  to 
all  the  dorsal  vertebrae,  and  to  all  the  vertebral  ribs.  The  anterior 
parts  of  the  vertebrae  of  the  neck  are  supplied  with  air  through  the 
passage  accommodating  the  vertebral  artery.  The  posterior  parts 
of  the  vertebrae  are  supplied  by  extensions  from  the  interspinal 
canal.  The  first  extensions  obtain  entrance  to  the1  anterior  seg- 
ments by  one  or  more  openings  of  the  inner  wall  of  the  intertrans- 
verse  canals;  the  median  extensions  penetrate  the  posterior  seg- 
ments by  two  openings,  a  right  and  a  left,  situated  on  the  inner  wall 
of  those  segments.  The  first  dorsal  vertebra  is  supplied  with  air 
in  the  same  manner,  by  the  middle  and  the  lateral  canals  of  the 
neck.  This  air,  after  passing  through  the  first  vertebra,  leaves  by 
a  lateral  exit  to  enter  a  small  air-sac.  From  this  it  passes  into  the 
superior  part  of  the  second  vertebra,  escapes  from  this  through  its 
lower  portion,  to  be  received  into  a  lateral  sac,  and  so  on  to  the  last 
.dorsal  vertebra.  These  sacs  also  supply  the  vertebral  ribs  with 
air,  which  enters  them  by  very  small  openings  located  on  their  spinal 
extremities. 

The  diaphragmatic  air-sacs  do  not  have  communications  with  the 
bones. 

The  abdominal  air-sacs  communicate  with  the  sacrum,  the 
coccygeal  vertebrae,  the  iliac  bones,  and  the  femurs.  The  air 
passing  through  the  sacrum,  the  coccyx,  and  the  ilium  comes  directly 
from  the  supra-renal  extensions;  the  air  which  fills  the  femoral  cavity 
comes  from  the  femoral  extensions. 

In  some  birds  these  air  spaces  are  more  greatly  developed  than  in 


THE    RESPIRATORY   APPARATUS  205 

others.  The  bones  that  are  always  aerated  in  all  birds  are  the 
cervical  and  the  dorsal  vertebrae,  the  sternum,  and  the  humeri. 
Those  aerated  in  some  kinds  only  are  the  furculum,  the  scapulae^ 
the  vertebral  and  the  sternal  ribs,  the  sacrum,  the  coccyx,  and  the 
femurs.  Those  that  are  never  aerated  are  the  bones  of  the  forearm, 
the  hand,  the  leg,  and  the  foot. 

The  service  of  air  to  the  bones  in  most  parts  of  the  body  by  the 
air-sacs,  as  just  shown,  is  in  special  cases  otherwise  rendered.  The 
Eustachian  tubes  furnish  air  to  the  bones  of  the  cranium  and  to  the 
upper  jaw;  while  the  lower  jaw  receives  air  from  the  pneumatic 
foramen  situated  upon  each  ramus  behind  the  tympanic  articulation, 
and  from  an  air  cell  which  surrounds  the  joint. 

The  cavities  of  the  embryonic  bones,  which  afterward  become 
pneumatic,  are  filled  with  marrow.  Selenka  states  that  the  invasion 
of  the  bones  by  the  air  is  a  late  development,  and  that  in  the  humerus 
this  invasion  occurs  after  the  twenty-second  day  in  the  life  of  the 
chick. 

Hunter  and  Compar,  who  have  made  extensive  researches,  con- 
sider the  function  of  the  air-sacs  as  threefold. 

First,  the  air-sacs  are  subsidiary  respiratory  organs,  which  aid 
in  ridding  the  blood  of  waste  products  and  in  taking  in  oxygen. 

Second,  they  aid  mechanically  the  actions  of  respiration  in  birds. 
During  the  act  of  inspiration  the  sternum  is  depressed,  the  angle 
between  the  vertebral  and  the  sternal  ribs  is  made  less  acute,  and 
the  thoracic  cavity  proportionately  enlarged;  the  air  then  rushes 
into  the  lungs  and  into  the  thoracic  receptacles,  while  those 
of  the  abdomen  become  flaccid.  When  the  sternum  is  raised,  or 
approximated  toward  the  spine,  part  of  the  air  is  expelled  from  the 
lungs  and  the  thoracic  air-sac  through  the  trachea,  and  part  is 
driven  into  the  abdominal  receptacles,  which  are  thus  alternately 
enlarged  and  diminished  with  the  expansion  and  the  contraction  of 
the  thorax.  Hence  the  lungs,  notwithstanding  their  fixed  condition, 
are  subject  to  due  compression  through  the  medium  of  the  contigu- 
ous air  receptacles,  and  are  affected  equally  and  regularly  by  every 
motion  of  the  sternum  and  of  the  ribs. 

Third,  they  reduce  decidedly  the  specific  gravity  of  the  whole 
body.  This  must  necessarily  follow  from  the  large  spaces  filled  with 
air  as  well  as  from  the  absence  in  the  bones  of  marrow  and  other 
fluids.  The  air-sacs  by  their  position  also  render  equilibrium  more 
stable. 


ANGIOLOGY 

The  Circulatory  Apparatus. — The  circulatory  apparatus  consists  of 
two  tubular  systems:  the  blood  vascular  system  and  the  lymphatic 
system. 

The  blood  vascular  system  consists  of  the  heart,  the  arteries,  the 
veins,  and  the  capillaries. 

The  heart  is  the  central,  propelling  organ.  The  arteries  form  a 
series  of  efferent  tubules,  which,  by  branching,  constantly  increase 
in  number  and  decrease  in  caliber,  and  which  serve  to  carry  the 
blood  from  the  heart  to  the  tissues.  The  capillaries  are  extensions 
from  these  latter  tubules  into  which  the  arteries  empty,  and  through 
the  walls  of  which  the  interchange  of  elements  between  the  blood 
and  the  other  tissues  takes  place.  The  veins  form  a  system  of 
converging  tubules  which  receive  the  blood  from  the  capillaries, 
decrease  in  number  and  increase  in  size  as  they  approach  the  heart, 
and  return  the  blood  to  that  organ. 

The  lymphatic  system  consists  of  capillaries  and  veins  alone. 
As  in  the  blood  system,  the  lymph  capillaries  collect  the  effete  mate- 
rial and  pour  it  into  the  lymph  veins,  and  these  in  turn,  carry  it  to 
the  large  blood  veins  adjacent  to  the  heart. 

Both  these  systems  have  one  and  the  same  continuous  lining, 
which  consists  of  a  single  layer  of  endothelial  cells.  In  the  heart 
this  lining  is  called  the  endocardium,  and  in  the  vessels,  the  endo- 
thelium.  It  forms  a  perfectly  smooth  surface. 

THE  HEART  (Fig.  21,  No.  7) 

The  heart  of  the  domestic  fowl  is  located  in  the  median  line  of 
the  thoracic  cavity.  It  is  more  anterior  and  mesial  .than  in  mam- 
mals. Its  axis  is  parallel  with  the  axis  of  the  trunk.  The  lungs 
being  confined  to  the  dorsal  part  of  the  trunk,  the  lower  part  of 
the  heart  is  not  surrounded  by  them,  but  extends  backward,  the 
apex  resting  in  the  anterior  part  of  the  anterior  median  fissure  of  the 
liver. 

The  heart  has  the  form  of  an  acute  cone  (Fig.  50,  No.  i),  the  apex 
of  which  is  bluntly  rounded. 

206 


ANGIOLOGY  207 

The  heart  is  surrounded  by  a  sere-fibrous  sac,  the  pericardium. 
This  sac  adheres  to  the  cervical  air  reservoirs  anteriorly  and  to  the 
diaphragmatic  septum  posteriorly.  It  is  composed  of  two  mem- 
branous layers:  the  parietal,  external,  dense,  and  fibrous;  and  the 
visceral,  internal,  and  serous.  The  pericardial  sac  has  no  direct 
attachment  to  the  heart,  except  at  the  upper  extremity  where  it 
surrounds  the  large  vessels  emerging  from  it.  The  serous  layer  is 
reflected  over  the  outer  portion  of  the  heart,  where  it  is  called  the 
epicardium.  The  function  of  the  pericardium  is  to  prevent  friction 
during  the  beating  of  the  heart.  It  contains  a  small  amount  of 
serous  fluid  for  perfect  lubrication.  This  fluid  is  called  the  liquor 
pericardii. 

Internally  the  heart  has  four  cavities:  two  auricles  and  two 
ventricles.  The  right  "ventricle  is  more  crescent-shaped  than  in 
solipedes,  arid  in  a  manner  envelops  the  left  ventricle  in  front  and  to 
the  right,  though  it  does  not  reach  the  point  of  the  heart.  The 
right  auricle  is  larger  than  the  left.  The  auricula-ventricular  valve 
is  not  tricuspid  as  in  mammals.  This  valve  instead  of  being  formed 
as  usual  by  a  membranous  curtain,  with  margins  retained  by  cords 
fixed  to  the  walls  of  the  ventricles,  is  composed  of  a  wide  muscular 
leaf,  which  appears  to  be  a  portion  of  the  inner  wall  of  the  ventricle 
detached  from  the  interventricular  septum.  This  septum  is  convex; 
and  the  auriculo-ventricular  orifice  is  an  oblique  slit  situated  between 
it  and  the  muscular  valve  in  question;  so  that,  when  the  heart  wall 
contracts  at  the  systole,  the  valve  is  applied  against  this  septum  a,nd 
closes  the  passage.  The  bicuspid,  or  auriculo-ventricular  valve  of 
the  left  side  usually  has  two  segments,  though  occasionally  there 
may  be  three.  The  fossa  ovalis  is  a  depression  behind  the  posterior 
semi-lunar  valve  in  the  septum  of  the  heart.  The  membranous  sep- 
tum closing  the  foramen  ovale  is  complete  and  strong  but  thin  and 
transparent.  The  right  auricle  receives  the  blood  from  the  two 
venae  cavae  coming  from  the  anterior  extremity,  and  from  the 
posterior  vena  cava.  These  empty  into  a  sinus.  The  left  auricle 
has  two  vessels,  the  pulmonary  veins  which  bring  blood  to  it  from 
the  lungs. 

Structure  of  the  Heart. — The  heart  is  lined  by  a  serous  membrane, 
the  endocardium,  which  is  a  continuation  of  the  endothelium  of  the 
blood-vessels.  There  are  a  few  muscular  pillars  in  the  inner  wall, 
called  the  columns  carnce.  To  give  the  heart  its  pumping  power, 
it  is  made  up  of  contractile  tissue,  a  specialized  kind  of  muscle 


208  ANATOMY    OF   THE   DOMESTIC   FOWL 

called  heart  muscle.  It  is  involuntary-striated  and  occupies  an 
intermediate  position,  both  morphologically  and  embryologically, 
between  smooth  involuntary  muscle  and  striated  voluntary  muscle 
(Fig.  74,  No.  4).  It,  like  striated  voluntary  muscle,  is  both  trans- 
versely and  longitudinally  striated.  Heart  muscle  cells  are  short, 
thick  cylinders,  which  are  joined  end  to  end  to  form  long  fibers.  By 
means  of  lateral  branches  the  cells  of  one  fiber  anastomoses  with 
cells  of  adjacent  fibers.  Each  cell  of  heart  muscle  contains  one 
centrally  located  nucleus.  There  is  no  distinct  sarcolemma,  but 
the  sarcoplasm  is  more  dense  near  the  surface  of  the  cell,  which 
gives  it  the  appearance  of  an  enveloping  cell  wall.  There  is  a 
zone  free  from  fibrillae  around  the  nucleus.  The  longitudinal 
fibrillae,  which  make  up  the  cell,  are  held  together  by  a  cement- 
like  substance. 

The  main  mass  of  the  heart  wall,  called  myocardium,  consists  of 
the  specialized  muscular  tissue  just  described.  The  myocardium 
differs  in  thickness  in  different  parts  of  the  heart  wall.  It  is  thickest 
in  the  left  ventricle  and  thinnest  in  the  auricles.  The  left  ventricle 
forces  the  blood  through  the  systemic  circulation  and  hence  must 
be  thicker  to  give  it  more  power  than  is  needed  for  the  right  ventricle, 
which  forces  the  blood  only  through  the  lungs.  The  auricles  are 
thinnest  of  all;  for  they  receive  the  blood  and  pass  it  only  to  the 
chambers  below.  The  auricular  appendages  at  the  base  of  the  heart 
in  fowls  are  not  so  well  marked  as  in  mammals.  The  auricular 
muscles  consist  of  an  outer  coat  common  to  both  auricles,  the  fibers 
of  which  are  transverse  and  of  an  inner  coat,  independent  for  each 
auricle,  the  fibers  of  which  are  longitudinal.  Between  the  two 
coats,  occur  bundles  of  muscle  the  fibers  of  which  run  in  various 
directions.  The  disposition  of  the  muscle  tissue  of  the  ventricles 
is  much  more  complicated.  It  is  composed  of  several  layers  of 
fibers  intricately  interwoven. 

The  endocardium,  covering  the  inner  surface  of  the  myocardium, 
forms  a  serous  lining  of  all  the  chambers  of  the  heart.  At  the 
arterial  and  venous  openings  it  is  continuous  with  and  similar  in 
structure  to  the  intima  of  the  vessels.  The  endocardium  consists 
of  two  layers,  an  external  layer  closely  attached  to  the  myocardium 
and  consisting  of  mixed  fibers,  including  those  of  elastic  tissue  and 
smooth  muscle  cells;  and  an  inner,  single  layer  of  endothelial  cells, 
spoken  of  above. 

The  heart  is  supplied  with  nutrient  blood  by  the  two  coronary 


ANGIOLOGY  2OQ 

arteries,  which  are  given  off  from  the  common  aorta  just  above  the 
semi-lunar  valves. 

A  right,  or  anterior,  and  a  left,  or  posterior,  coronary  from  their 
point  of  origin,  turn  in  a  ventral  direction  between  the  root  of  the 
aorta  and  the  pulmonary  artery,  the  right  going  to  the  right  coronary 
groove  and  the  left  to  the  left  coronary  groove  in  the  crown  furrow. 
From  here  they  send  branches  into  the  heart.  The  anterior,  right, 
coronary,  or  coronaria  dextra,  the  larger,  is  given  off  from  the 
inferior  wall  of  the  aorta.  It  divides  into  a  ramus  superficialis 
and  a  ramus  profundus.  The  ramus  superficialis  enters  the  crown 
furrow  and  divides  into  two  or  three  branches  on  the  right  heart 
wall.  These  branches  extend  to  the  apex  of  the  heart.  Twigs  from 
this  artery  along  its  course  extend  into  the  muscular  wall  reaching 
the  posterior  of  the  coronary  groove  where  they  anastomose  with 
those  of  the  left  coronary,  the  ramus  profundus,  and  with  other 
branches  from  the  same  artery.  The  ramus  profundus,  larger  than 
the  preceding,  gives  off  fine  branches  into  the  walls  of  the  aorta  and 
of  the  pulmonary  artery,  then  enters  from  behind  into  the  right  wall 
of  the  septum  ventriculorum,  extends  into  the  apex  of  the  heart,  and 
supplies  the  septum,  or  right  inner  chamber  wall  with  the  last  branch, 
this  breaking  through  the  posterior  wall  of  the  auricular  appendage. 

The  posterior,  left  coronary,  or  coronaria  sinislra,  originates  from 
the  dorsal  wall  of  the  aorta,  proceeds  as  one  branch  on  the  upper 
surface  of  the  left  auricular  appendix,  and  then  extends  between  the 
left  appendix  and  the  pulmonary  artery  to  the  ventral  surface  of  the 
heart.  On  the  left  side  it  supplies  the  wall  of  the  pulmonary  artery 
and  gives  off  a  ramus  profundus.  It  sometimes  divides  into  two 
parts  and  supplies  the  ventral  wall  of  the  right  chamber  and  then 
extends  to  the  left  wall  of  the  septum  medium.  The  rest  of  the 
coronaria  sinistra  enters  into  the  left  crown  furrow  as  the  ramus 
superficialis,  which  provides  the  left  and  dorsal  upper  surface  of 
the  left  chamber  to  the  apex.  From  this  furrow  it  extends  into  the 
left  chamber  and  the  left  appendage,  and  finally  fuses  with  the 
ramus  superficialis  of  the  coronaria  dextra. 

THE  BLOOD-VESSELS 

The  blood-vessels  consist  of  arteries,  veins  and  capillaries. 

The  Structure  of  the  Capillaries  and  Arteries. — The  capillaries 

are  minute  vessels  which  connect  the  arterioles,  or  terminal  arteries, 
u 


210  ANATOMY   OF   THE  DOMESTIC  FOWL 

with  the  venules,  or  terminal  veins.  They  are  only  from  6  to  14 
microns  in  diameter.  Their  walls  consist  of  a  single  layer  of 
endothelial  cells,  which  are  somewhat  elongated  in  the  long  axis 
of  the  vessels.  Their  edges  are  serrated,  and  are  united  by  a  small 
amount  of  intercellular  cement-like  substance.  Capillaries  branch 
without  diminution  in  caliber,  and  these  branches  anastomose  to 
form  capillary  networks,  the  meshes  of  which  differ  in  size  and  shape 
in  different  tissues  and  organs.  The  largest  meshed  networks  occur 
in  the  serous  membranes  and  hi  the  muscles;  and  the  smallest  occur 
in  the  glands,  such  as  the  liver. 

The  walls  of  the  arteries  are  thick  and  stand  open  when  empty, 
owing  to  the  elastic  tissue  contained  in  their  walls,  while  the  walls 
of  the  veins  collapse  when  empty,  owing  to  their  containing  a  smaller 
amount  of  elastic  tissue.  The  arterial  wall  is  provided  with  three 
coats:  tunica  intima }  or  inner  coat;  tunica  media,  or  median  coat; 
and  tunica  adventitia,  or  outer  coat. 

The  tunica  intima  consists  of  a  single  layer  of  endothelial  cells, 
continuous  with  and  similar  to  that  forming  the  walls  of  the  capil- 
laries. In  passing  from  the  capillaries  to  the  arterioles,  there  is  first 
a  thin  coat,  or  sheath-like  layer,  of  connective  tissue  around  the 
outside  of  the  endothelial  tubes.  Further  along,  isolated  smooth 
muscle  cells  arranged  in  a  circular  manner  occur  between  the  endo- 
thelial layer  and  the  layer  of  connective  tissue,  this  structure 
forming  vessels  called  precapillary  arteries.  Further  along  still, 
the  muscle  cells  form  a  complete  layer;  in  this  section  the  vessels 
are  called  arterioles  and  are  made  up  of  three  coats:  the  inner  endo- 
thelial, the  middle  muscular,  and  the  outer  fibrous. 

In  arteries  of  medium  size  the  intima  consists  of  the  endothelial 
layer,  a  layer  of  delicate  white  and  elastic  fibers,  connective-tissue 
cells,  and  the  membrana  elastica  interna,  or  an  outer  layer,  the 
elastic  layer,  of  the  intima. 

The  media  consists  of  a  thick  coat  of  circularly  arranged  smooth 
muscle  cells,  its  thickness  depending  largely  upon  the  size  of  the 
vessels.  There  is  also  a  small  amount  of  fibrillary  connective  tissue, 
which  supports  the  muscle  cells.  Elastic  tissue  is  present  in  the 
media,  the  amount  depending  on  the  size  of  the  vessel,  the  larger 
the  vessel  the  more  elastic  tissue  there  is  present.  In  the  large 
arteries  coarse  elastic  fibers  intermingle  with  the  finer  ones.  When 
much  elastic  tissue  is  present  the  muscle  cells  are  separated  into 
more  or  less  well-defined  groups. 


ANGIOLOGY  211 

The  adventitia  is  composed  of  loose  connective  tissue  with  some 
elastic  fibers.  A  few  smooth  muscle  cells  are  present,  which,  as  are 
also  the  elastic  fibers,  are  arranged  longitudinally.  The  adveniitia, 
blending  with  the  connective  tissue  surrounding  the  arteries,  serves 
to  anchor  the  vessels  to  the  surrounding  structure. 

Structure  of  the  Veins. — In  many  respects  the  walls  of  the  veins 
resemble  those  of  the  arteries.  The  same  three  coats  exist  and  the 
same  elements  enter  into  their  structure.  The  transition  from  capil- 
lary to  small  veins,  and  from  those  to  larger  veins,  is  similar  to  the 
transition  from  the  arteries  to  capillaries,  in  inverse  order.  The 
walls  are  not  so  thick  as  those  of  arteries.  The  elastic  tissue  is 
much  less  in  quantity  and  in  smaller  veins  disappears.  There  is 
not  a  clear  line  of  demarcation  between  the  intima  and  the  media. 

The  veins  of  birds  differ  from  those  of  mammals  in  that  they  have 
fewer  valves.  The  valves  are  also  less  perfect,  and  often  permit  a 
backward  flow  of  blood. 

The  walls  of  the  arteries  and  of  the  veins  are  supplied  with  nutri- 
ent blood-vessels.  These  are  called  the  vasa  vasorum,  or  blood-ves- 
sels of  the  blood-vessel  wall.  They  are  mostly  in  the  adventitia. 
They  may  arise  from  the  vessel  to  which  they  are  distributed  or  take 
origin  from  an  adjacent  vessel.  These  small  arteries  supplying  the 
vessel  coat  after  terminating  into  capillaries  form  small  veins  through 
which  the  blood,  from  the  structure  of  the  vessel  wall,  is  returned. 

The  walls  of  the  blood-vessels  are  supplied  with  both  medullated 
and  non-medullated  nerves.  The  non-medullated  nerve  fibers  are 
axones  of  the  sympathetic  neurones  and  control  the  caliber  of  the 
vessels.  These  fibers,  are  called  the  vasomotor  nerves.  They  form 
plexuses  in  the  adventitia,  from  which  are  given  off  branches  which 
penetrate  the  media  and  terminate  on  the  muscle  cells.  The  medul- 
lated nerves  are  the  axones  of  the  spinal  nerves.  The  larger  fibers 
are  found  in  the  connective  tissue  outside  the  adventitia  and  give 
off  branches  to  the  media  where  they  divide  repeatedly,  lose  their 
sheath,  and  terminate  in  the  media  and  at  times  in  the  intima. 

TKE  ARTIHIAL  TIUNKS 

The  common  aorta  is  short;  it  originates  from  the  left  ventricle 
(Fig.  61.6,  No.  K,  14),  and  is  guarded  by  three  semi-lunar  valves.  The 
aorta  breaks  through  the  pericardium  just  to  the  right  of  the  pul- 
monary arteries  in  a  ventral  direction;  it  then  turns  upward  dorsally 
and  to  the  right  of  the  inferior  bodies  of  the  vertebrae.  It  is  then 


212 


ANATOMY   OF   THE   DOMESTIC   FOWL 


directed  anteriorly,  and  dorsally  to  the  right  bronchus,  between  the 
right  bronchus  and  the  right  lung.  The  right  and  the  left  coro- 
naries  are  given  off  from  the  common  aorta;  they  have  been  dis- 
cussed. There  is  next  given  off  the  left  brachio-cephalic  or  brachio- 
cephalic  sinister  artery  (Fig.  6iB,  No.  K,  10),  which  is  just  above  the 
border  of  the  base  of  the  heart.  This  artery  passes  upward  and  slightly 


FIG.  6iB. 

K.  The  arterial  trunks.  I,  The  middle  sacral  artery.  2,  The  hypogastric 
artery.  3,  The  posterior  mesenteric  artery.  4,  The  ischiadic  artery.  5,  The 
femoral  artery.  6,  The  renal  artery.  7,  The  left  pectoral  artery  or  thoracico 
caudalis.  8,  The  left  axillary  artery.  9,  The  left  carotid  artery.  10,  The  left 
brachio-cephalic  artery,  n,  The  right  carotid  artery.  12,  The  right  brachial 
artery.  13,  The  right  pectoral  artery.  14,  The  common  carotid  artery.  15, 
The  posterior  aorta.  16,  The  celiac  axis.  17,  The  anterior  mesenteric  artery. 
18,  The  right  brachio-cephalic  artery.  19,  The  auricular  portion  of  the  heart. 
20,  The  ventricular  portion  of  same.  21,  Sterno-clavicular  artery.  22,  Anterior 
thoracic. 

L.  The  venous  trunks,  i,  The  caudal  vein.  2,  The  coccygeo-mesenteric 
vein.  3,  The  posterior  mesenteric  vein.  4,  The  anterior  mesenteric  vein.  5, 
The  gastro-duodenal  vein.  6,  The  portal  vein.  7,  The  hepatic  vein.  8,  The 
left  anterior  vena  cava.  9,  The  left  pectoral  vein.  10,  The  left  brachial  vein. 
ii.  The  left  jugular  vein.  12,  The  right  jugular  vein.  13,  The  right  brachial 
vein.  14,  The  right  pectoral  vein.  15,  The  right  anterior  vena  cava.  16,  The 
posterior  vena  cava.  17,  The  common  iliac  vein.  18,  The  femoral  vein.  19, 
The  renal  vein.  20,  The  internal  iliac  vein.  21,  The  hypogastric  vein.  22, 
The  auricular  portion  of  the  heart.  23,  The  ventricular  portion  of  same. 

forward,  over  the  center  of  the  inferior  larynx.  Just  beyond  this 
point  the  subclavian  artery  is  given  off;  this  artery  later  becomes  the 
axillary  and  the  axillary  the  brachial  artery.  Then  there  is  given 
off  the  anterior  and  the  posterior  thoracic  arteries;  and  finally,  the 
pectoral,  which  supply  the  pectoralis  muscles  and  later  terminate 
in  the  carotid,  the  vertebral,  and  the  cervical  arteries.  The  carotid 


ANGIOLOGY 


2I3 


artery  gives  off  an  esophageal  artery.  The  other  arterial  trunk  given 
off  from  the  common  aorta  is  the  right  brachio-cephalic  or  brachio- 
cephalic  dexter  (Fig.  6iB,  No.  K,  18).  The  right  brachio-cephalic 
artery  gives  off  the  subclavian,  which  continues  as  the  axillary, 
and  continues  as  the  brachial  artery.  There  is  given  off  the  anterior 
and  the  posterior  thoracic,  the  right  carotid  (Fig.  6iB,  No.  K,  n),  the 
vertebral,  and  the  dorsal.  The  last  continues  as  the  cervical. 

The  pulmonary  arterial  trunk  is  given  off  from  the  conus  arteriosus 
of  the  right  ventricle.  It  is  guarded  at  its  origin  by  three  semi-lunar 
valves  similar  to  those  of  the  aorta.  The  trunk  divides  into  two 
pulmonary  arteries,  which  are  short,  one  called  the  pulmonalis 
dexter  and  the  other  the  pulmonalis  sinister.  The  former  goes  to 

BRANCHES  OF  THE  BRACHIO-CEPHALIC  ARTERY 

Thyroidea 


Brachio-cephalic 


Truncus 
caroticus 


Vertebralis 


Cervicalis  inferior 

Vertebralis  anterior 

Vertebralis  posterior 

Arteria  cervicalis  ascendens 
Bronchiales 
Inferior  esophageal 
Subcutaneous  colli 

Carotis  cerebralis 

Cervicalis  superior 

Occipitalis 

Carotis  externa 
Spinalis  anterior  (  Basilaris  (  Cerebelli  inferior 


Carotis 
communis 


Subclavia 


(  Clavicularis 

Sterno-clavicularis    |  Sternalis 

I  Acromialis 

Subscapularis 

Ulnaris 

Axillaris 

Brachialis 

Brachialis  profunda 

Radialis 

Humeralis 

Circumflex  humer- 

I 

alis  anterior 

Thoracica  externa 

Thoracalis 

Thoracica  inferior  f  Art.e™thor- 
(   acicalonga. 

Mammaria  interna 

I  Circumflex  humeralis  posterior 
Collateral  ulnaris 
I  Collateral  radialis 


2I4 


ANATOMY   OF    THE   DOMESTIC   FOWL 


the  right  and  the  latter  to  the  left  lung.  Each  branch  penetrates 
the  lung  near  the  bronchus.  These  arteries  divide,  or  branch, 
similarly  to  the  bronchi.  Following  the  branchings  of  the  bronchi, 
they  finally  terminate  into  the  lung  capillaries,  forming  networks 
on  the  bronchi  and  the  air-tube  terminals. 

The  cord-like  remnant  of  the  ductus  botalli,  or  embryonal  connec- 
tion between  the  lung  arterial  trunk  and  the  anterior  aorta,  has 
been  observed  but  is  rare  in  grown  birds. 

The  arteries,  the  veins,  and  the  lymphatic  vessels  of  birds  anas- 
tomose far  more  frequently  than  those  of  mammals. 

BRANCHES  OF  THE  ARTERIA  CAROTIS  CEREBRALIS  INTERNA 


Carotis  cerebralis 


Occipitalis 

'  Occipitalis  sublimis 
.  Occipitalis  profunda  (  Meningea 

Temporalis 

f  Rete  temporale 

Ophthalmica 

Recurrent   ophthal-    |  Rete  ethmoidaiis 

externa 

micum                        I  Ethmoidaiis 

Plexus  palpebralis 

Plexus  alveolaris  inferior 

Plexus  muscularis 

Plexus  temporalis 

Plexus  lacrimalis 

Ramus  ciliaris  posticus 

Meningea  media 

Sphenoidea 

Ethmodalis 

Spheno-maxillaris         (  Ethmoi- 

extern  a 

Ophthal-    1    dalis 

Ethmoidal  is 

mica  in-    I 

in  terna 

Cere- 

terna 

.  bralis 

Ramus 

Sylviae 

anterior 

Cerebralis  profunda  [  Choroid  plexus 

Carotis  externa 


Arteria  centralis  retinae 
Ramus  posterior 

BRANCHES  OF  THE  ARTERIA  CAROTIS  EXTERNA 

Hyoidea 

Laryngea  superior 
Facialis 
Lingualis 


BRANCHES  OF  THE  ARTERIA  CAROTIS  FACIALIS 

Auricularis 


Facialis 


Facialis  interna  }  Alveolaris  inferior 
Maxillaris  interna 
Facialis  externa 


Mentalis 


ANGIOLOGY  215 

BRANCHES  or  THE  CAROTID  TRUNK 

The  carotis  communis  artery  springs  from  the  carotid  trunk  .of 
the  brachio-cephalic.  It  is  directed  horizontally,  ascending  to  the 
ventral  side  of  the  neck.  It  then  extends  downward  to  the  inferior 
median  neck  region.  Just  after  leaving  its  origin  it  gives  off  several 
small  branches  to  the  bronchi  and  to  the  esophagus,  and  extends 
toward  the  head.  The  carotid  lies  on  the  thyroid  gland  and  at  this 
point  touches  the  jugular  vein  (Fig.  21).  At  this  point  the  thyroid 
arteries  are  given  off  from  the  carotid  trunk.  The  thyroid  gland 
also  receives  blood  from  the  bronchialis  artery. 

Dorsalward  and  near  the  thyroid  gland  the  carotid  artery  gives 
off  a  branch  (the  bronchialis)  which  accompanies  the  recurrent 
laryngeal  nerve,  along  the  inferior  larynx  and  the  bronchi,  and 
supplies  the  lung  substance  and  that  part  of  the  esophagus  in  this 
region. 

The  vertebral  artery  is  given  off  from  the  carotid  trunk,  dorsal- 
ward  to  the  thyroid  gland,  and  on  the  left  side.  The  right  vertebral 
artery  may  be  given  off  from  the  brachialis  dextra  or  right  brachialis. 

The  inferior  esophageal  artery  is  given  off  from  the  ventral  side 
of  the  carotid,  supplies  the  esophagus,  extends  then  to  the  skin  of 
the  neck  and  to  the  trachea,  is  directed  anteriorly  toward  the 
head  and  anastomoses  with  the  vertebral  artery.  This  artery  ac- 
companies the  vagus  nerve  and  forms  a  collateral  artery  to  the 
carotid  and  the  vertebral  artery. 

The  subcutaneous  colli  springs  from  the  carotid  artery  near 
the  thyroid  gland  and  communicates  with  the  inferior  cervical  artery, 
which,  in  turn  springs  from  the  vertebral  artery. 

The  Common  Carotid. — Near  the  last  cervical  vertebra  the  two 
carotid  arteries  occupy  the  same  channel,  to  which  they  are  attached 
by  fascia,  and,  lying  close  to  the  inferior  surface  of  the  bodies  of  the 
cervical  vertebrae,  are  covered  by  the  colli  muscles.  Near  the  third 
or  the  fourth  cervical  vertebra,  the  two  carotid  arteries  separate. 
Near  the  atlas  each  carotid  divides  into  the  carotis  cerebralis  and 
carotis  externa.  Near  this  division  the  superior  cervical  artery 
branches  off.  This  latter  artery  extends  down  the  neck  in  company 
with  the  pneumogastric  nerve  and  the  jugular  vein,  supplies  the 
skin  and  the  neck  muscles,  and  anastomoses  with  the  inferior  cer- 
vical artery  and  the  subcutaneous  colli  artery. 


2l6  ANATOMY    OF   THE   DOMESTIC   FOWL 

The  occipital  artery  originates  either  from  the  carotis  communis 
or  sometimes  from  the  superior  cervical. 

BRANCHES  OF  THE  CAROTIS  CEREBRALIS 

The  branches  of  the  carotis  cerebralis  are  as  follows: 

1.  The  occipitalis  (Fig.  72,  No.  18),  which  in  turn  gives  off,  first, 
the  occipitalis  sublimis.     The  occipitalis  sublimis  supplies  the  outer 
and  the  middle  portion  of  the  digastricus  and  the  posterior  mylo- 
hyoideus  muscle.     It  also  gives  off,  second,  the  occipitalis  profunda 
which    supplies  the  inner  portion  of   the  digastricus  muscle  and 
becomes  the  meningeal  artery,  which  passes  through  the  foramen 
vagi,  entering  the  brain  cavity,  where  it  supplies  the  coverings  of 
the  brain  as  far  as  the  sella  turcica.     Superficial  branches  of  this 
artery  are  distributed  to  the  muscles  in  the  region  of  the  atlas  and 
anastomose  with  the  vertebral  artery. 

2 .  The  ophthalmica  externa,  which  passes  below  the  articulation 
of  the  quadrate  bone,  around  the  tympanic  cavity,   enters  the 
canalis  caroticus,  and  passes  into  the  cranial  cavity.     The  ramus 
occipitalis,  passing  out  of  the  same  foramen,  again  enters  the  diploe 
of  the  cranium;  then  after  passing  dorsally  over  the  upper  outer 
semicircular  canal  of  the  ear,  passes  backward  through  the  occipital 
bone. 

The  ophthalmica  externa  (Fig.  72,  No.  9)  forms  a  main  trunk  and 
gives  off  two  branches:  the  temporal  artery  and  the  recurrent 
ophthalmic.  The  recurrent  ophthalmic  gives  off  the  rete  temporalis, 
rete  ethmoidalis,  a  branch  to  the  orbital  gland,  and  finally  anastomo- 
ses with  its  own  branches  and  with  those  of  the  internal  ophthalmic 
at  the  olfactory  foramen  and  aids  in  forming  the  ethmoidal  artery. 
These  arteries  supply  blood  by  giving  off  branches  to  the  muscles 
of  the  eye,  sclerotic  coat,  iris,  choroid  coat,  and  the  ciliary  bodies. 
It  gives  off  another  branch  to  Harder's  gland,  and  finally  anastomo- 
ses with  the  ethmoidalis. 

3.  The  plexus  temporalis,  rete  mirabile  ophthalmicum,  or  won- 
derful network  (Fig.  72,  No.  8),  is  formed  between  the  second  and 
the  third  trunk  of  the  trigeminus  nerve  and  the  rete  ophthalmicum. 

Inferior  to  this  is  the  alveolar  plexus,  which  plexus  accompanies 
the  third  branch  of  the  trigeminus  into  the  lower  jaw.  Two  main 
branches  form  this  plexus,  one  coming  from  the  carotis  facialis,, 
which  anastomoses  with  the  alveolar  artery. 


ANGIOLOGY  217 

The  palpebral  plexus  lies  between  the  trunks  of  the  trigeminus, 
and  supplies  mainly  the  lower  eyelid. 

The  plexus  muscularis  extends  to  the  fifth  portion  of  the  temporal 
muscle. 

The  plexus  lacrimalis  forms  on  the  posterior,  orbital  wall  on  the 
ramus  ethmoidalis  and  supplies  the  lacrimal  gland  and  the  upper 
eyelid.  It  anastomoses  with  branches  from  the  facial  artery. 

The  ramus  ciliaris  posticus  supplies  the  inferior  rectus  and  the 
external  rectus  muscle  of  the  eyeball.  It  anastomoses  with  the 
ophthalmica  externa. 

The  median  meningeal  artery  passes  through  the  foramen  occupied 
by  the  second  branch  of  the  trigeminal  nerve.  Passing  into  the 
cranial  cavity,  it  supplies  the  dura  mater.  Before  passing  into  this 
foramen,  small  branches  are  given  off,  which  supply  the  skin  and  the 
temporal  muscle;  and  some  branches  anastomose  with  the  superior 
cervical  and  the  ethmoidal  arteries. 

4.  The  Cerebral  Artery. — Each  cerebral  artery  enters  the  cranial 
cavity  through  the  canalis  caroticus  located  in  the  sphenoid  bone, 
passes  forward  medially  from  the  cochlea,  dorsally  from  the  Eusta- 
chian  tube,  and  passes  through  a  small  canal  which  opens  on  the 
inner  surface  of  the  sella  turcica.  Originating  in  this  foramen,  the 
sphenoid  artery  divides  into  two  branches  which  anastomose  with 
the  pterygoidean  and  the  pterygo-pharyngeal  artery  and  which 
supply  the  upper  jaw  and  the  throat  regions. 

The  spheno-maxillaris  artery  supplies  the  gums. 

The  right  and  the  left  cerebral  arteries  unite  at  the  sella  turcica. 
After  this  union  they  divide  again  immediately  and  pass  to  the 
base  of  the  brain,  where  they  give  off  twigs  to  the  optic  nerve,  to 
the  optic  chiasm,  and  where  also  is  given  off  the  arteria  retinae 
centralis.  Passing  posteriorly  each  cerebral  artery  gives  off  the 
ramus  posterior,  and  then  passes  to  the  side  of  the  cerebellum. 

The  basilar  artery,  a  continuation  of  the  anterior  spinal  artery,  is 
located  ventrally  and  mesially  to  the  cerebellum.  Laterally  and 
inferiorly  the  basilar  artery  gives  off  the  inferior  cerebellar  artery. 

The  ramus  anterior  is  given  off  from  the  cerebralis  artery  and 
continues  as  the  internal  ophthalmic  artery.  The  ramus  anterior 
also  gives  off  the  sylman  artery,  which  supplies  the  sides  of  the  cere- 
brum and  the  middle  brain.  In  the  fissure  between  the  hemi- 
spheres and  the  optic  thalamus  is  located  the  arteria  cerebri  profunda. 
This  artery  passes  along  the  median  surface  of  the  cerebrum  and  in 


2l8  ANATOMY   OF    THE   DOMESTIC    FOWL 

its  course  supplies  the  adjacent  parts.  It  enters  into  the  formation 
of  the  choroid  plexus  of  the  lateral  ventricle. 

The  internal  ophthalmic  artery  extends  out  of  the  cranial  cavity, 
through  the  optic  foramen,  into  the  orbital  cavity.  It  passes 
upward  along  the  interorbital  wall  and  supplies  the  optic  nerve, 
the  trigeminus  nerve  trunk,  and  the  eye  muscles,  and  dorsally 
anastomoses  near  the  olfactory  nerve  with  the  rete  ethmoidale  and 
the  external  ophthalmic  artery,  and  continues  as  the  ethmoidal 
artery. 

The  ethmoidal  artery  supplies  the  supra-orbital  gland  and  the 
gland  of  Harder.  It  gives  off  twigs  to  the  rete  ophthalmicum  and 
other  branches  to  the  skin  of  the  frontal  region,  where  it  anastomoses 
with  branches  of  the  external  facial  artery.  These  branches  in 
the  frontal  region  are  rather  large.  Large  branches  are  given  off 
to  the  comb. 

The  arteria  ethmoidalis  externa  originates  in  the  nasal  cavity  from 
a  division  of  the  ethmoidal  artery. 

The  external  ethmoidal  artery  passes  below  the  lacrimal  bone, 
extends  forward,  supplies  the  walls  of  the  nasal  cavity,  and  finally 
sends  a  branch  anteriorly  into  the  upper  median  portion  of  the  jaw 
bone,  and  other  branches  to  the  septum  nasi  and  other  parts  of  the 
nasal  cavity. 

There  are  frequent  anastomoses  between  the  ethmoidalis  interna, 
the  facialis,  and  the  spheno-maxillary  artery. 

The  internal  ethmoidal  artery  supplies  principally  the  posterior 
turbinated  bones  and  septum  nasi. 

BRANCHES  OF  THE  EXTERNAL  CAROTID  ARTERY 

Branches  from  the  external  carotid  and  the  facial  artery  supply 
the  tongue  and  its  muscles,  the  larynx,  the  lower  jaw  bone,  the 
gums,  and  the  upper  lateral  facial  region. 

The  external  carotid  (Fig.  62,  No.  ^4,8)  gives  off  the  following 
branches: 

First,  the  hyoid  artery  (Fig.  72,  No.  12)  which  supplies  the  inner 
portion  of  the  depressor  mandibular  and  also  the  cornua  of  the 
os  hyoideum,  and  extends  to  the  tip  of  the  tongue. 

Second,  the  superior  laryngeal  artery  (Fig.  72,  No.  16)  which 
supplies  the  sterno-brachialis  and  gives  off  branches  which  extend 
downward  to  the  trachea  and  to  the  esophagus.  The  main  artery 


ANGIOLOGY 


219 


FIG.  62. 

A.  Blood-vessels  of   the   head,     i,   The  cerebellum.     2,   The  cerebrum.     3, 
The   semicircular  canals.     4,   Sinus  occipitalis   superior.     5,    Sinus  temporalis 
sphenoideus.     6,  Sinus  transversus  dexter.     7,  Superior  esophageal  artery.     8, 
Carotis  externus.     9,  Lingual  artery.     10,  Sinus  longitudinalis. 

B.  Veins  of  the  antero-inferior  part  of  the  head  and  neck,     i,  The  right  carotid 
artery.     2,  The  left  carotid  artery.     3,  Vena  jugularis  dexter.     4,  Vena  verte- 
bralis  dexter.     5,  Transverse  vein.     6,  Vena  cephalica  dexter  anterior.     7,  Vena 
lingualis.     8,  Vena  cephalica  posterior.     9,  Vena  facialis  externa  dexter.     10, 
Vena  infrapalatina.     n,  Posterior  nares.     12,  Vena  facialis  interna.     13,  Vena 
facialis  externa  sinister. 

C.  The  brain,     i,    Medulla  oblongata.     2,   Cerebellum.     3,   Optic  lobe.     4. 
Cerebrum.     5,  Longitudinal  fissure.     6,  Transverse  fissure.     7,  Olfactory  nerve. 
8,  Optic  nerve.     9,  Optic  commissure.     10,  Motor  oculi.     n,  Patheticus.     12, 
Trigeminal,  or  trifacialis.     13,  Abducens.     14,  Facialis.     15,  Auditory,  or  acous- 
ticus.     16,  Glosso-pharyngeus.     17,  Pneumogastric.     1 8,  Spinal  accessory.     19, 
Hypoglossus.     20,    Hypophysis.     21,   Crus  cerebri.     22,   Ganglion  on  superior 
nerve  trunk.     23,  Spinal  cord.     24,  A  pair  of  spinal  nerves. 


220  ANATOMY   OF   THE   DOMESTIC   FOWL 

passes  along  the  left  side  of  the  esophagus  and  anastomoses  with 
branches  of  the  inferior  esophageal,  forming  collateral  circulation 
in  that  region. 

Third,  the  lingualis  artery  (Fig.  62,  No.  Ag)  which  lies  between  the 
mylo-hyoideus  and  the  posterior  part  of  the  hyoid  bone.  It  sup- 
plies the  tongue  muscles.  It  passes  to  the  median  surface  of  the 
lower  jaw  bone,  where  are  given  off  small  branches  which  enter 
the  jaw  and  anastomose  with  the  inferior  alveolar  artery. 

Fourth,  the  Facial  Artery. — The  facial  artery  divides  into  the 
following  branches: 

The  auricular  artery  is  given  off  near  the  articulation  of  the  os 
quadratum  with  the  os  zygomaticum.  It  is  located  at  the  outer 
auditory  canal,  and  its  branches  are  distributed  to  the  parotid 
region  and  to  the  depressor  mandibular,  or  digastricus,  muscle. 

The  external  facial  artery  is  located  between  the  os  quadratum  and 
the  masseter  muscle.  It  gives  off  a  branch  to  the  lower  jaw  bone 
and  to  the  skin  of  that  region,  and  then  passes  to  the  lacrimal  bone 
and  supplies  branches  to  the  commissure  of  the  mouth,  the  auditory 
canal,  the  masseter  muscle,  the  three  eyelids  (upper  and  lower  eye- 
lids and  the  membrana  nictitans),  the  nose  cavity,  and  the  skin  in 
the  frontal  region.  It  communicates  on  the  other  side  with  the 
ethmoidal  artery. 

The  internal  facial  artery  passes  over  and  through  the  os  ptery- 
goideum,  supplies  all  the  jaw  muscles,  and  is  continued  as  the  inferior 
alveolar  artery. 

The  inferior  alveolar  artery  enters  the  canal  of  the  lower  jaw  bone 
along  with  the  mandibular  nerve.  It  is  finally  continued  as  the 
mental  artery,  leaving  the  canal,  and  passing  to  the  outer  jaw  surface. 

The  facialis  continues  as  the  internal  maxillary  artery. 

The  internal  maxillary  artery  (Fig.  72,  No.  15)  supplies  the  ptery- 
goid  muscle,  the  upper  part  of  the  pharynx,  the  commissure  of  the 
mouth,  the  salivary  gland  region,  the  gums,  and  finally  anastomoses 
with  branches  of  the  spheno-maxillaris  artery. 

BRANCHES  OF  THE  VERTEBRAL  ARTERY 

The  vertebral  artery  is  given  off,  dorsally  near  the  thyroid  gland, 
from  the  carotis  communis  or  from  the  carotid  trunk.  The  verte- 
bral artery  passes  horizontally  and  dorsally  into  the  canals  formed 
in  the  transverse  processes  of  the  cervical  vertebrae.  After  it 
leaves  the  carotid,  it  is  divided  into  anterior  and  posterior  branches. 


ANGIOLOGY  221 

The  posterior  vertebral  artery  passes  in  the  canals  of  the  trans- 
verse processes  of  the  fifth  or  sixth  dorsal  vertebra.  It  sends 
branches  into  the  vertebrae,  into  the  spinal  canal,  and  into— the 
intercostal  musdes  between  the  ribs  and  anastomoses  with  the 
intercostal  arteries. 

The  anterior  vertebral  artery  is  larger  than  the  posterior.  It 
extends  laterally  along  the  side  of  the  neck  in  the  foramen  of  the 
transverse  processes  of  the  cervical  vertebrae,  and  lies  along  the 
course  of  the  inferior  vertebral  vein  and  the  deep  imbedded  trunk 
of  the  sympathetic  nerve.  It  continues  to  the  head.  In  its  passage 
it  gives  off  to  each  vertebral  segment  a  dorsal  and  a  ventral  branch. 
Twigs  from  these  branches  pass  into  the  bodies  of  the  vertebrae  and 
the  spinal  canal,  giving  nutriment  to  the  bony  structure  and  to  the 
spinal  cord  and  its  coverings.  Other  twigs  are  distributed  to  the 
muscles  of  the  neck  and  some  finally  anastomose  with  branches  of 
the  carotis  communis.  This  artery,  reaching  the  head,  gives  off  a 
long  anastomosing  branch  which  passes  between  the  atlas  and 
posterior  part  of  the  occipital  bone  and  joins  the  ramus  profundus 
and  the  occipital  artery,  thus  again  communicating  with  the  carotid 
artery.  The  remainder  of  the  vertebral  artery  is  small  and  passes 
through  the  foramen  magnum  into  the  cranial  cavity  where  it 
anastomoses  with  terminal  branches  of  the  cerebral  artery.  At  the 
base  of  the  neck  and  before  the  vertebral  artery  enters  the  canal  of 
the  cervical  vertebrae,  it  gives  off  the  arteria  cermcalis  ascendens, 
superior  artery  of  the  crop  (Fig.  73,  No.  18)  which  branches  out  on 
the  upper  surface  of  the  crop  is  also  distributed  to  the  neck  muscles, 
and  later  subdivides  into  the  transverse  cervical  arteries  which 
supply  the  skin  and  the  muscles  of  the  base  of  the  neck,  and  the 
shoulder  region. 

On  the  ventral  side  of  the  neck  there  are  given  off  two  subvertebral 
carotid  arterial  branches.  They  lie  in  a  shallow  furrow  on  the 
ventral  side  of  the  cervical  vertebrae  and  close  to  the  median  line. 

BRANCHES  OF  THE  SUBCLAVIAN  ARTERY 

The  subclavian  artery  (Fig.  20,  No.  13;  Fig.  73,  No.  n)  gives  off 
the  following  branches: 

i.  Sterno-clavicularis  (Fig.  73,  No.  9)  which  originates  on  the 
upper  part  of  the  subclavia,  between  the  carotid  artery  and  external 
thoracic  (Fig.  73,  No.  3),  divides  into  many  branches.  The  sterno- 


222  ANATOMY   OF   THE   DOMESTIC   FOWL 

clavicularis  gives  off  the  sternal  artery,  which  enters  by  the  side  of  the 
supra-coracoid  muscle  and  the  anterior  rim  of  the  sternum.  It  is 
distributed  to  the  inner  surface  and  over  the  air-sac.  Another 
outside  branch  passes  the  posterior  end  of  the  crista  sterna  and 
supplies  the  large  breast  muscles. 

The  clavicular  artery  (Fig.  73,  No.  8)  accompanies  the  clavicle  to 
the  shoulder-joint. 

The  acromial  artery  is  given  off  from  the  sterno-clavicularis  on 
the  ligament  near  the  shoulder-joint. 

2.  The  thoracic  artery  branches  from  the  subclavian  artery  (Fig. 
70,  No.  4).    The  thoracic  artery  gives  off  the  following  branches: 

The  internal  mammary,  or  internal  thoracic  artery  (Fig.  73,  No.  16) 
arises  on  the  inner  side  of  the  sternum  and  extends  downward  and 
backward,  giving  nutrient  branches  to  the  anterior  vena  cava  and 
to  the  diaphragm.  At  the  point  of  the  costo-sternal  muscle  it 
divides  into  an  inner  and  an  outer  branch. 

The  inner  branch  supplies  the  costo-sternal  muscle  and  extends 
along  the  ribs  and  along  their  juncture  with  the  breast-bone.  It 
finally  extends  posteriorly,  giving  numerous  branches  to  the  abdom- 
inal muscles.  The  outer  branch  is  distributed  in  a  similar  manner, 
giving  off  branches  to  the  diaphragm  and  to  the  abdominal  muscles, 
and  anastomoses,  on  the  surface  of  the  abdominal  muscles,  with  the 
epigastric  artery. 

The  external  thoracic  artery  (Fig.  73,  No.  3),  ramus  superior, 
supplies  principally  the  large  breast  muscles. 

The  inferior  thoracic  artery,  external  ramus  inferior,  passes  along 
the  outside  of  the  pectoralis  major  muscle,  extends  downward, 
and  gives  off  the  arteria  thoracica  longa  (subcutaneous  thoracic). 
This  latter  artery  supplies  the  skin  of  the  breast  region.  Other 
branches  are  given  off  to  the  muscles  of  the  breast  and  to  the  skin 
of  the  region,  and  some  finally  anastomose  with  the  branches  of  the 
sternal  artery. 

3.  The  axillary  artery  (Fig.  73,  No.  12)  extends  out  of  the  thoracic 
cavity  along  with  the  brachial  nerve  plexus.     It  gives  off  the  sub- 
scapular  is  which  supplies  the  muscles  of  the  scapular  region.    The 
axillary  artery  terminates  as  the  brachialis  which  passes  between 
the    biceps    brachii  and  anconeus  muscles  downward  along  the 
humeral  shaft.    It  gives  off  the  anterior  humeral  circumflex  artery 
and  the  brachialis  profunda  artery  (Fig.  68,  No.  3).     It  gives  off 
near  the  elbow-joint  the  ulnar  and  radial  arteries. 


ANGIOLOGY  223 

The  (interior  circumflex  humeral  artery  passes  through  the  short 
head  of  the  biceps  and  gives  off  a  branch  to  the  biceps  muscle, 
supplying  the  insertional  part  of  the  breast  muscles. 


BRANCHES  or  THE  BRACHIALIS  PROFUNDA 

The  brachialis  profunda  artery  (Fig.  68,  No.  3)  continues  as  the 
posterior  circumflex  humeral  artery.  This  artery  supplies  the  mus- 
cles of  the  posterior  part  of  the  humerus,  the  skin  of  the  wing,  and 
the  muscles  of  the  brachial  region.  The  trunk  of  the  arteria  brachii 
profunda  passes  downward  along  the  anconeus  muscle,  supplying 
that  muscle  and  giving  off  the  collateral  ulnar  artery.  On  the  ulnar 
olecranon  it  anastomoses  with  the  recurrent  ulnar,  thus  establishing, 
at  this  region,  collateral  circulation.  The  rest  of  the  brachialis 
sends  branches  to  the  biceps  muscle  and  to  the  skin  of  the  upper 
arm,  and  finally  gives  off  the  arteria  collateralis  radialis,  which 
supplies  the  condylo-ulnaris.  It  then  anastomoses  with  the  end 
branches  of  the  recurrent  radialis  artery. 

The  radial  artery  (Fig.  67,  No.  4)  passes  downward  on  the  outer 
rim  of  the  forearm.  It  continues  down  to  the  carpal  region,  where 
it  supplies  the  muscles  and  the  skin  of  the  carpal  region  it  gives  off 
the  recurrent  radial,  which  passes  on  the  middle  finger  and  finally 
anastomoses  with  the  collateral  radialis  artery. 

The  ulnar  artery  (Fig.  68,  No.  6  and  9)  passes  downward  on  the 
inner  surface  of  the  ulna  to  the  carpal  region  where  it  gives  off  a 
branch  to  the  wing  plexus  and  divides  into  two  branches,  the  smaller 
branch  supplying  the  thumb  (Fig.  68,  No.  7).  This  branch  passes 
down  the  radial  side  of  the  middle  finger  to  the  last  joint  of  the 
second  finger.  The  larger  (Fig.  68,  No.  8)  lies  between  the  second 
and  the  third  finger  bones,  and  passes  through  a  slit  between  these 
two  bones  to  the  flexor  side  of  the  hand  and  extends  to  the  last 
finger- joint,  supplying  the  structures  in  the  region.  The  ulnar 
artery  gives  off  a  small  arterial  twig  to  the  papilla  of  each  large  wing 
feather  (Fig.  67,  No.  6). 

The  recurrent  ulnar  passes  backward  to  the  olecranon  of  the  ulna 
and  supplies  the  muscles,  the  skin,  the  feathers,  and  other  structures 
of  the  region,  and  terminates  in  end  collateral  ulnar  branches 
(Fig.  67,  No.  5). 


224 


ANATOMY   OF   THE   DOMESTIC  FOWL 


Posterior 
aorta 


BRANCHES  OF  THE  POSTERIOR  AORTA* 

Esophageal 

Intercostales 

Dorsal 

Lumbars 

Spermatics 

Renals 

Ovarian 

Recurrent  esophageal 

Recurrent  intestinalis   ( Recurrent  ilio-colicus 
Celiac      Posterior  or  recurrent  sinister   f  Renalis 
axis        Anterior  or  recurrent  dexter      I  Splenics 

f  Hepatic 

Hepatica  dextra       ~        . 
I  Gastric 

0        ,.  .    f  Coccygeae  laterales 

Sacrahs  media  ,  _  ,.    (  _  .• 

(  Coccygea  media    Coccygeae  laterales 


( Recurrent  ilio-celiacus 
I  Recurrent  superior  hemorrhoidal 
Posterior  mesenteric  ( Median  hemorrhoidal 

Recurrent  renalis 

Tibialis  postica 

Tibialis  antica  [  Peroneal  ( Anterior  tibial  plexus 

Arteria  ovarialis 


Anterior  mesenteric 


Ischiadica 


Pudenda  communis 


Crural 
(External  iliac) 


f  Renalis 

Hemorrhoidalis  intima 
I  Pudenda  externa 

[  Internal  pelvic  (umbilical) 


Circumflex  femoris 
Femoralis 


The  posterior  aorta  (Fig.  63,  No.  2)  passes  backward  along  the 
inferior  part  of  the  bodies  of  the  dorsal  and  lumbo-sacral  vertebrae. 
In  the  thoracic  cavity  it  lies  dorsal  to  the  esophagus.  It  gives 
branches  (esophageal)  only  to  the  esophagus  during  its  passage  as  far 
as  the  seventh  dorsal  vertebra.  Following  this  point  there  are  given 
of  several  pairs  of  arteries  which  divide  into  a  superior  and  an  infe- 
rior branch.  The  superior  branch  extends  upward  and  anastomoses 
with  branches  of  the  vertebral  artery  and  other  twigs  coming  from 
the  intercostal  arteries.  These  latter  arteries  given  off  are  small 
dorsal  arteries.  The  inferior  branches  extend  downward  between 
the  ribs  and  supply  the  intercostal  muscles.  The  intercostal  arteries 

1  Nomenclature  used  by  Bronn. 


ANGIOLOGY 


225 


do  not  take  their  origin  from  the  aorta  in  numerous  and  regular 
branches  as  in  mammals;  they  consist  originally  of  but  few  vessels, 
which  are  multiplied  by  anastomoses  with  each  other  and  with 
the  arteries  which  come  out  of  the  spinal  canal.  An  arterial  plexus 
is  thus  formed  around  the  head  of  each  rib,  from  which  a  vessel 
is  sent  to  each  of  the  intercostal  muscles  and  ribs  and  are  continued 


FIG.  63. — The  vascular'  system  injected,  i,  The  heart.  2,  The  posterior 
aorta.  3,  The  right  brachiocephalic  artery.  4,  The  left  brachiocephalic  artery. 
5,  The  anterior  mesenteric  artery  showing  its  many  branches  and  anastomoses 
near  and  on  the  intestines.  It  is  accompanied  by  branches  of  the  mesenteric 
vein.  6,  The  rectal  branch  of  the  posterior  mesenteric  artery.  7,  The  duodenal 
loop  and  pancreas  showing  the  pancreatic  artery.  8,  The  anus.  9,  The  cloaca. 
10,  The  liver,  n,  The  lungs.  12,  The  right  subclavian  artery.  13,  The  right 
carotid  artery.  14,  The  right  anterior  vena  cava.  15,  The  subclavian  vein. 
16,  The  right  jugular  vein.  17,  The  carotid  trunk.  18,  The  posterior  vena  cava. 

into  the  muscles  upon  the  outside  of  the  body  and  its  integuments. 
The  anastomosis  of  the  intercostal  arteries  round  the  ribs  is  similar 
to  the  plexus,  which  is  produced  by  the  great  sympathetic  nerve  in 
the  same  location.  The  lumbar  arteries  are  given  off  farther  pos- 
teriorly and  along  the  lumbar  region.  The  lumbar,  like  the  dorsal 
branches  are  given  off  in  pairs.  These  arterial  branches  pass  along 
the  thigh  and  the  upper  sacral  vertebral  region,  and  supply  those 
parts.  Ventrally  they  are  covered  by  the  kidneys  and  pass  into 

15 


226 


ANATOMY   OF   THE  DOMESTIC  FOWL 


the  abdominal  muscles.  The  posterior  aorta  gives  off  the  spermatic 
arteries  and  the  ovarian  artery.  In  the  male  the  former  supply 
the  testes.  The  ovarian  artery  of  the  female  gives  off  a  twig  to  each 
calyx  containing  an  ovum.  Each  calyx  is  voluminously  supplied 
with*!blood.  Next  the  renal  arteries  are  given  off  to  the  kidneys. 


n  1.9 


FIG.  64. — The  splanchnic  arteries,  veins  and  nerves,  i,  A  portion  of  the  left 
testes.  2,  Adrenal  gland.  3,  Anterior  lobe  of  kidney.  4,  Heart.  5,  Liver. 
6,  Second  portion  of  the  esophagus.  7,  Proventriculus.  8,  Gizzard.  9,  Spleen. 
10,  Duodenal  loop,  n,  Pancreas.  12,  Blind  extremity  of  caecum.  13,  Float- 
ing portion  of  small  intestine.  14,  Rectum.  15,  Cloaca.  16,  Anus.  17, 
Celiac  axis.  1 8,  Ureter.  19,  Vas  deferens.  20,  Recurrent  sinister  artery.  21, 
Anterior  recurrent  dexter  artery.  22,  Arteria  hepatica  dextra.  23,  Recurrent 
esophageal  artery.  24,  Recurrent  intestinalis  artery.  25,  Ilio-colicus  artery. 
26,  Anterior  mesenteric  artery.  27,  Recurrent  branches  of  the  same.  28,  Ilio- 
cceliacus  artery.  29,  Recurrent  superior  hemorrhoidal  artery.  30,  Posterior 
mesenteric  artery.  31,  Crural  arteries.  32,  Sacralis  media  artery.  33,  Recur- 
rent renalis.  34,  Middle  renal  lobe.  35,  Posterior  renal  lobe.  36,  Vena  mesen- 
tericus  communis.  37,  Vena  hemorrhoidalis.  38,  Vena  pancreatico-duodenalis. 
39,  Vena  proventriculo-leinealis.  40,  Vena  portalis  dextra.  41,  Ischiadic  nerve. 
42,  Thoracic  sympathetic  trunk.  43,  Anter'or  splanchnic  plexus.  44,  Spinal 
nerves.  45,  Posterior  splanchnic  nerve  plexus.  46,  Intestinal  nerve  trunk. 
47,  Vena  renalis  magna. 

The  celiac  axis  (Fig.  64,  No.  17)  originates  near  the  seventh  ster- 
nal vertebra  and  to  the  right  of  the  esophagus,  breaks  through  the 
diaphragm,  and,  near  this  point,  gives  off  a  recurrent  esophageal 
(Fig.  64,  No.  23).  The  celiac  axis  gives  off  three  main  branches: 
The  anterior  or  recurrent  dexter,  the  posterior  or  recurrent  sinister,. 


ANGIOLOGY  227 

the  recurrent  intestinalis,  all  of  which  lie  to  the  right  of  the  spleen, 
under  the  left  lobe  of  the  liver,  and  along  the  left  side  of  the  stomach. 
The  recurrent  sinister  (Fig.  64,  No.  20)  gives  arterial  branches  4o 
the  proventriculus,  the  gizzard,  the  pyloris,  and  the  left  lobe  of  the 
liver.  The  anterior  or  recurrent  dexter  (Fig.  64,  No.  21)  gives  off  a 
renal  artery  and  from  four  to  six  splenic  arteries. 

The  recurrent  intestinalis  artery  (Fig.  64,  No.  24)  arises  on  the 
posterior  of  the  stomach  within  the  duodenal  loop,  and  supplies 
the  duodenum  and  the  pancreas  (Fig.  63,  No.  7).  It  gives  off  a 
branch,  called  the  recurrent  ilio-colicus  (Fig.  64,  No.  25),  which 
supplies  the  large  intestines,  including  the  caeca. 

The  arteria  hepatica  dextra  (Fig.  64,  No.  22)  is  a  branch  from  the 
celiac  axial  trunk.  It  gives  several  branches  to  the  right  lobe  of 
the  liver  and  to  the  gall-bladder.  The  gastric  branches  pass  to 
the  muscles  of  the  stomach.  The  anterior  and  posterior  recurrent 
branches  often  anastomose. 

The  anterior  mesenteric  artery  (Fig.  63,  No.  5;  Fig.  64,  No.  26) 
originates  from  the  posterior  aorta  near  the  generative  glands.  It; 
is  directed  downward,  and  divides  into  many  branches  which  pass 
in  the  mesentery  toward  the  intestines.  Recurrent  branches  (Fig. 
64,  No.  27)  are  given  off,  which  anastomose,  forming  mesenteric 
arches.  '  From  these  arches  are  given  off  branches  which  supply  the 
intestinal  walls. 

The  anterior  mesenteric  artery  gives  off  the  recurrent  ilio-celiacus 
(Fig.  64,  No.  28)  which  is  distributed  to  the  caeca;  other  of  its 
branches  are  distributed  to  the  small  intestine. 

The  anterior  mesenteric  artery  extends  along  the  small  intestine 
and  ends  in  the  recurrent  superior  hemorrhoidal  arteries  (Fig.  64,  No. 
29)  which  anastomoses  on  the  surface  of  the  rectum  with  a  branch 
of  the  posterior  mesenteric  artery. 

Branches  from  the  anterior  mesenteric  artery  also  anastomose 
with  branches  of  the  celiac  axis. 

The  posterior  mesenteric  artery  (Fig.  64,  No.  30)  is  given  off  from 
the  posterior  aorta  posterior  to  the  origin  of  the  anterior  mesenteric 
and  near  the  arteries  of  the  thigh  and  is  distributed  to  the  lesser 
mesentery  supplying  the  large  intestine.  Branches  of  the  superior 
hemorrhoidal  arteries  anastomose  with  branches  of  the  posterior 
mesenteric  artery.  Branches  from  this  source  are  called  the  median 
hemorrhoidal  (Fig.  63,  No.  6). 

The  posterior  mesenteric  artery  (Fig.  64,  No.  30)  also  gives  off  a 


228  ANATOMY   OF    THE   DOMESTIC   FOWL 

long  branch  to  the  cseca.  Branches  of  the  posterior  mesenteric 
artery  anastomose  with  branches  of  the  anterior  mesenteric. 

The  crural  arteries  (Fig.  64,  No.  31)  are  given  off  in  a  pair  from 
the  posterior  aorta.  They  pass  through  the  mass  of  the  lobes  of  the 
kidneys,  at  about  the  median  region,  and  extend  out  of  the  pelvic 
cavity  in  front  of  the  spine  and  ilio-pubic  ligament. 

The  crural,  or  the  external  iliac  artery,  is  divided  into  three 
branches  as  follows: 

First,  the  internal  pelvic,  or  umbilical  artery,  is  given  off  just  as 
the  cruralis  leaves  the  pelvic  cavity.  It  passes,  as  a  long  vessel, 
on  the  inner  surface  of  the  lumbo-sacral  bones  and  supplies  the 


\ 


FIG.  65. — Blood-vessels  and  nerves  of  the  hind  extremity.  Inside  view  of  leg. 
I,  Ischiadic  nerve.  2,  Ischiadic  artery.  3,  Posterior  tibial  vein.  4,  Vena 
metatarsa  dorsalis  interna.  5,  Vena  metatarsalis  plantaris  profunda.  6,  Vena 
cruralis.  7,  Vena  metatarsalis  interna,  vena  magna.  8,  Vena  tibialis  postica. 
9,  Vena  metatarsa  magna.  10,  Nerves  of  the  toes,  n,  Vena  metatarsalis 
dorsalis  profunda. 

obturator  internus  muscle  and  extends  into  the  umbilical  region. 
It  gives  off  branches  to  the  abdominal  muscles,  and,  in  the  female,  a 
branch  is  distributed  to  the  ligament  of  the  oviduct. 

Second,  the  arteria  circumflex  femoris,  which  passes  between  the 
sartorius  and  vastus  internus  and  extends  dorsalward,  supplies 
the  sartorius  muscle,  the  vasti  muscles,  and  the  ilio-trochanteric 
region. 

Third,  the  femoral  artery,  which  passes  beside  the  vena  cruralis 
and  extends  down  the  posterior  surface  of  the  thigh  to  the  knee- 
joint,  supplies  the  upper  thigh  muscles  with  the  exception  of  the 
adductor  muscles. 


ANGIOLOGY 


229 


The  ischiadic  artery  (Fig.  69,  No.  9)  forms  the  main  artery  of  the 
posterior  extremity.  This  artery,  the  largest  vessel  of  that  region, 
is  given  off  from  the  posterior  aorta  and  passes  ventrally  over-and 


FIG.  66. — Blood-vessels  and  nerves  of  the  posterior  extremity.  Outside  view. 
I,  Anterior  tibial  artery.  2,  Metatarsal  artery.  3,  Digital  arteries.  4,  Vena 
cutaneous  crurus.  .5,  Ischiadic  artery.  6,  Vena  cruralis.  7,  Lateral  cutaneous 
branch  of  the  ischiadic  nerve. 

between  two  of  the  main  lobes  of  the  kidney.  The  continuation 
of  the  posterior  aorta  is  called  the  sacralis  media  (Fig.  64, 
No.  32).  The  ischiadic  artery  gives  off  a  recurrent  renalis  on  the 


FIG.  67. — Blood-vessels  and  nerves  of  the  fore  limb.  Outside  view,  i, 
Median  nerve.  3,  Ulnar  nerve.  4,  Radial  artery.  5,  Recurrent  ulnaris  artery. 
6,  Twigs  of  ulnar  artery  to  wing  feathers. 

posterior  lobe  of  the  kidney  (Fig.  64,  No.  33).  On  the  left  side  it 
gives  off  a  branch  to  the  oviduct  and  to  the  ligament  of  the  oviduct. 
The  main  trunk  leaves  the  cavity  with  the  ischiadic  nerve  (Fig.  65, 


230  ANATOMY   OF   THE   DOMESTIC   FOWL 

No.  i)  through  a  foramen  formed  by  the  os  ilium  and  the  os  ischium. 
It  sends  branches  into  the  adductor  muscles  of  the  upper  and  the 
lower  thigh.  It  gives  off  anastomotic  branches  which  unite  with 
those  from  the  femoral  artery.  At  the  flexure  of  the  knee-joint  it 
gives  off  two  branches  to  that  region  (Fig.  69,  No.  10).  It  gives  off 
another  branch  to  the  gastrocnemius  muscle  and  one  to  the  flexor 
perforans  digitorum.  It  terminates  in  the  anterior  and  posterior 
tibial  arteries. 

The    first,     the    tibialis    postica     (Fig.     69,     No.    12)    passes 
between  the  gastrocnemius  and  the  deep  flexors  giving  off  branches 


FIG.  68. — Blood-vessels  and  nerves  of  the  fore  limb.  Inside  view,  i,  Vena 
humeri  profunda.  2,  Brachialis  longus  inferior.  3,  Brachialis  profunda.  4, 
Radial  artery.  6,  Ulnar  artery.  7,  Ulnar  arterial  branch  to  thumb.  8,  Digital 
branch  of  ulnar  artery.  9,  Ulnar  artery. 

in  its  course  to  the  skin  and  to  other  parts,  and  disappears  shortly 
below  the  intertarsal  joint. 

The  second,  the  tibialis  antica  (Fig.  66,  No.  i;  Fig.  69,  No.  u), 
is  often  the  larger  of  the  two  arteries.  The  anterior  tibial  artery 
gives  off  branches  to  the  knee-joint  and  to  adjacent  structures.  It 
gives  a  large  branch  to  the  head  of  the  gastrocnemius  muscle.  It 
passes  to  the  posterior  surface  of  the  tibial  head  and  gives  off  the 
peroneal  artery,  which  passes  through  the  membrana  interossea 
located  between  the  tibia  and  fibula  giving  branches  to  the  anterior 
side  of  the  membrane  of  the  patellar  region  of  the  knee-joint.  It 
gives  branches  to  the  anterior  side  of  the  lower  thigh  and  finally 
terminates  subcutaneously  in  the  anterior  tibial  plexus. 

The  main  portion  of  the  anterior  tibial  artery  passes  downward 


ANGIOLOGY 


231 


along  the  posterior  surface  of  the  membrane  located  between  the 
tibia  and  fibula,  and  sends  branches  for  the  flexor  digitorum  com- 
munis  et  profundus.  It  then  breaks  through  the  membrane, 
reaches  the  anterior  side  and  there  communicates  with  the  anterior 
tibial  plexus.  It  gives  off  branches  to  the  muscles  on  the  anterior 
side  of  the  lower  thigh  and  the  skin,  and  passes  between  the  outer 
and  the  middle  malleolus  of  the  tarsal  bones.  It  passes  to  the 
plantar  surface  and  divides  between  the  toes.  In  addition  to  the 


FlG.  69. — Blood-vessels  and  nerves  of  the  femoro-tibial  region, 
the  tibia  removed. 


A  section  of 


A.  Veins,  arteries  and  nerves  dissected  as  in  B. 

B.  V,  Vein.     A,  Artery.     N,  Nerve,     i,  Vena  poplitealis.     2,  The  three  veins 
forming  the  vena  poplitealis.     3,  Vena  femoris  interna  profunda.     4,  Vena  femoris 
anterior.     5,  Vena  cruralis.     6,  Vena  cutanea  abdominalis  femoralis.     7,  Vena 
cutaneous  cruralis.     8,   Deep  vein  of  the  knee-joint.     9,  Ischiadic  artery.     10, 
Branches  of  ischiadic  artery  to  flexure  of  knee,     n,  Anterior  tibial  artery.     12, 
Posterior  tibial  artery.     13,  Ischiadic  nerve.     14,  Trunk  (a  branch  of  the  ischi- 
adic) which  gives  off  the  superficialis  peroneus  and  peroneus  profundus.     15, 
Median   branch   of   ischiadic   nerve.     16,    Superficialis   peroneus.     17,    Lateral 
branch  of  the  ischiadic  nerve. 

plantar  branches  there  are  given  off  dorsal  branches  between  the 
third  and  the  fourth  toes.  These  branches  form  the  direct  continua- 
tion of  the  dorsal  vessels  of  the  anterior  tibial  plexus. 

The  arteria  pudenda  communis  (Fig.  70,  No.  20)  passes  to  the 
depressor  coccygeus  muscle,  gives  off  a  branch  to  the  caudal  part 
of  the  kidney,  crosses  the  ureter,  provides  the  ischio-pubic  and 
pubio-coccygeus,  or  depressor  coccygis  lateralis,  muscles,  and  on 


232 


ANATOMY   OF    THE   DOMESTIC   FOWL 


the  lateral  rim  of  the  latter  muscle  it  gives  off  the  arteria  hemorrhoid- 
alis  intima.  This  artery  passes  to  the  bursa  of  Fabricius  and  to  the 
end  of  the  cloaca.  It  enters  into  the  ischio-coccygeus  muscle,  and 
divides  into  the  arteria  pudenda  externa,  and  in  ducks,  the  arteria 
profunda  penis.  These  branches  supply  the  vas  deferens,  the  ureter, 
the  cloaca,  the  penile  structure,  and  the  muscles  of  these  parts. 


'*•     «« 


FIG.  70. — Blood-vessels  of  a  Cornish  cock  i,  The  left  pulmonary  artery. 
2,  Right  pulmonary  artery.  3,  Left  brachio-cephalic  artery.  4,  Left  subclavian 
artery.  5,  Left  carotid  artery.  6,  Right  brachio-cephalic  artery.  7,  Posterior 
aorta.  8,  Posterior  vena  cava.  9,  Left  pulmonary  vein.  10,  Right  pulmonary 
vein,  ii,  Celiac  axis  12,  Anterior  mesenteric  artery.  13,  Ischiadic  artery. 
14,  Crop.  15,  Superior  artery  of  the  crop  and  vein  of  same  name.  16,  Testicular 
or  ovarian  artery.  17,  External  iliac  artery.  1 8,  Intercostal  nerve.  19,  Median 
sacral  artery.  20,  Arteria  pudenda  communis.  21,  Anus.  .  22,  Vena  hypo- 
gastrica.  23,  Right  vena  hepatica  magna.  24,  Left  vena  hepatica  magna.  25, 
Vena  iliaca  interna.  26,  Vena  iliaca  communis.  27,  Vena  iliaca  externa.  28, 
Vena  coccygo-mesenterica.  29,  Vena  umbilicalis.  30,  Vena  supra-renalis.  31, 
Origin  of  the  pars  renalis.  32,  Lumbar  veins.  33,  Vena  epigastrica.  34, 
Lumbales  (arteries).  35,  Anterior  division  of  the  lumbo-sacral  plexus.  36, 


Posterior  division    of   the   lumbo-sacral  plexus. 
38,  Right  anterior  vena  cava. 


37,  Left   anterior  vena  cava. 


The  Sacralis  Media. — The  median  coccygeal  artery  (Fig.  70, 
No.  19)  forms  the  single  extension  of  the  sacralis  media.  It  gives 
off  lateral  branches  between  the  caudal  vertebrae  which  supply  the 
dorsal  muscles  of  that  region  and  the  skin.  The  third  pair  are  the 
largest.  These  are  the  arteries,  coccygea  later  ales,  and  are  located 
on  the  dorsal  side  of  the  tail,  they  supply  the  tail  glands  and 
rudder  feathers,  the  main  tail  feathers,  or  rectrices.  A  small 
arterial  twig  is  given  off  to  the  papilla  of  each  rectrix. 


ANGIOLOGY  233 

THE  VENOUS  TRUNKS 

The  venous  blood  enters  the  lungs  from  the  right  ventricle  through 
the  two  pulmonary  arteries  (Fig.  70, .No.  i  and  3). 

The  two  pulmonary  veins  (Fig.  70,  No.  9  and  10)  collect  the  ar- 
terial blood  from  the  lungs,  and  empty  it  into  the  left  auricle. 

There  are  three  venae  cavae  which  collect  the  systemic  blood  and 
empty  it  into  the  right  auricle.  These  venae  cavae  are  two  anterior 
(Fig.  70,  No.  37  and  38)  and  one  posterior  (Fig.  70,  No.  8). 

Each  anterior  vena  cava  is  formed  by  the  union  of  a  vena  jugu- 
laris,  a  vena  vertebralis,  and  a  vena  subclavicularis  (Fig.  63,  No.  15). 


FIG.  71. — Veins  of  the  liver  of  a  fowl.  i,  Vena  mesenterica  communis. 
2,  Vena  portalis  propria.  3,  Anterior  vena  mesentericus.  4,  Vena  portalis  dex- 
ter. 5,  Vena  portalis  sinister.  6,  Posterior  vena  cava.  7,  Celiac  axis.  8,  Base 
of  the  heart.  9,  The  liver.  •  10,  Hepatic  veins. 

The  jugular  vein  is  formed  by  the  union  of  the  vena  cephalica 
anterior,  and  the  vena  cephalica  posterior. 

The  jugular  vein  (Fig.  62,  No.  B  3)  passes  along  the  side  of  the  neck 
and  lies  near  the  trachea,  the  esophagus,  and  the  pneumogastric 
nerve.  Near  the  base  of  the  skull  the  two  jugular  veins,  the  right 
and  the  left,  are  connected  by  a  transverse  vein.  By  this  anasto- 
mosis part  of  the  blood  from  the  left  jugular  vein  is  sent  into  the 
right.  Therefore  the  right  jugular  vein  is  larger  than  the  left.  The 
jugular  veins  collect  the  blood  from  the  tongue  region,  the  thyroid, 
the  esophagus,  the  trachea,  the  crop,  and  other  structures  along  its 
course  through  the  cervical  region. 


234 


ANATOMY  OF   THE  DOMESTIC  FOWL 


The  vertebral  veins  are  divided  into  the  anterior  and  the  posterior, 
or  the  inferior  and  the  superior.  The  anterior  vertebral  vein  is  located 
in  the  cervical  region  and  collects  the  blood  from  the  brain  and  the 
inner  part  of  the  head.  The  vertebral  vein  passes  along  the  dorsal 
side  of  the  spinal  cord. 


BRANCHES  OF  THE  VEN^E  CAV^)  ANTERIORES 

Venae  linguales 

Vena  occipitalis  lateralis  [  Vena  occipito-collores 

Vena  ascendenes  lateralis 

Venae  colli  cutineae 

Venae  esophagealeae 

Venae  tracheales 

ularis 

arum  thyroidearum 
Vena  occipitalis   (  Sinus  foraminis 
interna  I    occipitalis 

Vena  in- 
Vena  vertebralis  posterior 

Vena  vertebralis  anterior 


Vena 

Vena  subscapi 

jugularis 

Venae  glandule 

Vena 

Vena  cava 

vertebralis 

anterior 

tercos- 
tales 


C  Vena  vertebralis 
Vena  vertebralis  lateralis  dorsalis    I  Venae  intercostales 


Venae  coronariae 
Vena  subclavicularis 
Vena  thoracica  interna 


Vena  intercostales 


Vena  facialis 
communis 


Vena  pharyngea  superior 

Vena  muscularis  depressoris  mandibularis 

Vena  muscularis  colli  anterior  superioris 

Vena  lingualis 

Vena  sublingualis  et  sphenoidea 


The  posterior  vertebral  vein  is  located  in  the  dorsal  region,  passes 
backward  and  receives  the  blood  from  the  dorsal  neck  region  and 
from  the  intercostal  veins  and  from  the  vertebral  segments  and 
adjacent  regions. 

The  anterior  and  the  posterior  vertebral  vein  form  one  trunk, 
the  vertebral  vein,  and  this  trunk  empties  into  the  vena  jugularis 
just  before  the  subclavian  and  the  jugular  unite. 

The  subclavian  vein  collects  the  blood  from  the  anterior  extremi- 
ties. It  unites  with  the  vena  jugularis  of  the  same  side. 

The  left  vena  cava  receives  the  coronary  veins  from  the  heart. 


ANGIOLOGY 
THE  VEINS  OF  THE  HEAD 


235 


BRANCHES  or  THE  VENA  FACIALIS  INTERNA 

The  vena  facialis  interna  (Fig.  62,  No.  12)  lies  dorsal  on  the  ptery- 
goid  bone  and  receives  the  vena  maxillaris,  the  vena  ophthalmica,  the 
vena  mandibularis  interna,  the  venae  pharyngeae  superiores,  and  the 
vena  retis  mirabilis  temporale. 


r 


i 

•BBBI  •••••  - 

FIG.  72. — Blood-vessels  and  nerves  of  the  abdominal  cavity  and  hind  extremity 
and  head.  I,  Vena  renalis.  2,  Vena  intervertebrales  sacrales.  3,  Posterior 
aorta.  4,  External  iliac.  6,  Ischiadic  nerve.  7,  Ischiadic  artery.  8,  Arterial 
rete]j  (plexus  temporalis).  9,  Ophthalmic  artery.  10,  Palatine  artery,  n, 
Lingual  artery.  12,  Hyoid  artery.  13,  14,  External  carotid  artery.  15,  Inter- 
nal maxillary  artery.  16,  Superior  laryngeal  artery.  17,  Superior  esophageal 
artery.  18,  Occipital  artery.  19,  Internal  carotid  artery. 

The  vena  maxillaris  comes  out  of  the  upper  beak  with  the  re- 
current trigeminus  nerve  and  then  passes  backward  between  the 
jugular  and  palatine  bones.  It  lies  medio-ventrally  to  the  eye- 
ball and  communicates  at  this  point  with  the  ophthalmic  vein.  It 
is  covered  ventrally  with  the  pterygoid  bone.  The  maxillary  vein 
collects  the  blood  from  the  gland  of  Harder,  the  upper  beak,  and 


236 


ANATOMY   OF   THE    DOMESTIC    FOWL 


receives  blood  from  the  vena  supra-palatina  and  from  the  lower 
jaw  bone  and  the  external  mandibular  vein.  It  also  receives  blood 
from  the  external  sublingual  vein,  and  the  sublingual  gland.  It 
follows  the  inner  rim  of  the  jaw  bone.  The  maxillary  vein  receives 
an  anastomosing  branch  from  the  cutaneous  facial  vein,  at  a  point 
near  the  commissure  of  the  mouth. 


FIG.  73. — Photograph  of  blood-vessels  and  nerves  of  the  thorax,  i,  Vena 
sternalis.  2,  Vena  thoracico-externa.  3,  External  thoracic  artery.  4,  Coracoid 
bone.  5,  Sternum.  6,  Shoulder- joint.  7,  Humerus.  8,  Clavicularis  artery. 
9,  Sterno-clavicularis  artery.  10,  Thoracico-humeralis  artery.  II,  Subclavian 
artery.  12,  Axillary  artery.  13,  Brachialis  profundus  artery.  14,  Ulnar 
artery.  15,  Radial  artery.  16,  Internal  mammary  artery.  17,  Superior  vein 
of  the  crop.  18,  Superior  artery  of  the  crop.  19,  Brachial  nerve  plexus.  20, 
Anterior  division  of  brachial  nerVfe  plexus.  21,  Posterior  division  of  brachial 
nerve  plexus. 

The  vena  ophthalmica  lies  close  to  the  point  where  the  olfactory 
nerve  passes  out  of  the  cranial  cavity.  The  largest  branch  it  re- 
ceives is  the  recurrent  ophthalmo-temporalis,  which  accompanies  the 
lateral  side  of  the  optic  nerve.  It  collects  the  blood  from  the  base 
of  the  brain,  from  Harder's  gland,  from  the  eye  muscles,  from  the 


ANGIOLOGY 


237 


Vena  cephalica 

anterior  or 

facialis 

communis 

Vena  jugularis 

or  cephalica 

communis 

Vena  subclavia 

Venae  vertebral  e 

Vena  cephalica 

posterior 

Vena  mandibularis  interna 
Vena  retis  mirabilis  temporalis 
Venae  pharyngeae  superiores 


inner  eye,  the  nose,  the  lacrimal  gland,  the  skin  of  the  frontal  region, 
and  the  comb. 

BRANCHES  OF  THE  VENA  JUGULARIS 

Vena  maxillaris 
Vena  ophthalmica 
Vena  f  acialis 
interna 

Vena  facialis  cutinea 
Vena  temporalis 
Vena  facialis    Vena  auricularis 
externa  Vena  palpebralis 

Vena  transversus 
Vena  retis  mirabilis  temporalis 


Sinus  cranii  et  cerebri 
Vena  carotis 

f  Sinus  fove£  cerebelli 
Vena  auris 


I  Vena  occipitalis  externa 


Vena  maxillaris 


Vena  jugularis  prima 
Vena  occipitalis 
Vena  lingualis 
Vena  mandibularis  externa 
Vena  sublingualis  externa 


.  Vena  supra-palatina 

Vena  ophthalmica  ( Vena  ophthalmo-temporalis,  recurrent 
Vena  facialis  communis  ( Vena  cephalica  externa 
Vena  occipitalis  externa  ( Vena  occipitalis  interna 
Vena  retis  mirabilis  temporalis  ( Vena  spheno-temporalis 
Sinus  foveae  cerebelli  ( Sinus  occipitalis  externa 

The  trunk  of  the  internal  facial  vein  receives  the  blood  of  the 
internal  mandibular  vein.  The  internal  mandibular  vein  emerges 
from  the  alveolar  canal  of  the  inferior  jaw  bone  and  receives  branches 
from  the  muscles  of  mastication. 

The  vena  retis  mirabilis  temporalis  passes  out  of  the  eye  cavity 
and  lies  between  the  internal  facial  vein  and  the  external  facial 
vein,  and  passes  around  the  os  quadratum  and  the  os  pterygoideum. 
It  receives  veins  from  the  outer  ear  region,  lacrimal  gland,  eyelids, 
and  the  spheno-temporalis. 


238  ANATOMY  OF   THE  DOMESTIC  FOWL 

The  venae  pharyngeae  superiores  are  the  veins  on  the  dorsal 
surface  of  the  pharynx.  These  veins  form  the  small  plexuses  which 
unite  with  the  two  trunks  of  the  facial  veins.  This  forms  an  anas- 
tomosis between  the  left  and  the  right  facial  veins. 

BRANCHES  OF  THE  EXTERNAL  FACIAL  VEIN 

The  vena  facialis  externa  (Fig.  62,  No.  B,  9)  lies  behind  the  quad- 
rate bone  and  is  partly  covered  ventrally  by  the  inner  extension 
of  the  lower  jaw  bone.  It  collects  the  blood  principally  from  the 
upper  region  of  the  cranium  and  the  face,  including  the  comb. 

The  vena  facialis  cutinea  receives  branches  from  the  muscles  in 
the  region  of  the  jaw,  the  lower  jaw  bone,  the  muscles  of  the  eyelids, 
the  frontal  region,  and  the  anastomotic  branches  from  the  vena 
maxillaris. 

The  vena  temporalis  is  made  up  of  veins  from  the  skin  of  the  tem- 
poral region,  the  masseter  and  the  tongue  muscles,  and  from  the 
sides  of  the  upper  throat  region. 

The  vena  palpebralis  is  made  up  from  veins  from  the  three  eye- 
lids and  the  temporal  region  near  the  eye.  Its  trunk  passes  lat- 
erally over  the  temporo-mandibularis  ligament.  The  vena  pal- 
pebralis collects  blood  from  the  lacrimal  gland,  the  eyelids,  and  the 
outer  ear  region. 

The  following  veins  empty  into  the  trunk  of  the  vena  facialis 
communis :  venae  pharyngis  superiores,  vena  muscularis  depressoris 
mandibulae,  vena  muscularis  colli  anterior  superioris,  vena  lin- 
gualis  et  hyoidea.  The  right  terminal  branches  of  the  vena  lin- 
gualis  empty  into  the  vena  cephalica  posterior. 

The  venae  pharyngis  superiores  and  vena  lingualis  et  hyoidea 
collect  blood  from  the  muscles  of  the  tongue  and  posterior  tongue 
region. 

The  vena  lingualis  et  hyoidea  (Fig.  62,  No.  B,  7)  collects  the  blood 
from  the  muscles  of  the  tongue  region,  the  lower  tongue  glands,  and 
the  upper  throat  region. 

Between  the  two  trunks  of  the  vena  facialis  communis  and  anterior 
to  the  entrance  of  the  vena  cephalica  posterior  there  is  an  anastomosis, 
the  vena  transversus  (Fig.  62,  No.  B,  5).  Through  this  anastomosis 
which  lies  crosswise  the  two  jugular  veins  are  influenced  in  different 
ways.  At  this  point  both  jugular  veins  are  of  the  same  size.  The 
anastomotic  branch  lies  crosswise.  Through  this  anastomosis  the 


ANGIOLOGY 


239 


right  receives  some  blood  from  the  left  head  region  indicating  that 
the  blood  flows  from  left  to  right.  This,  as  stated  before,  makes  the 
left  jugular  vein  the  smaller. 


BRANCHES  OF  THE  VENA  CEPHALICA  POSTERIOR 

The  left  vena  cephalica  posterior  (Fig.  62,  No.  B,  8)  communicates 
with  the  transverse  vein  (Fig.  62,  No.  B,  5).  The  left  receives  the 
smaller  veins  of  the  skin  region,  the  esophagus,  and  the  trachea. 
These  vessels  communicate  with  their  fellow  of  the  opposite  side 
and  with  the  vertebral  vein  of  the  same  side,  which  causes  a  gradual 
reduction  of  the  size  of  the  jugular  vein. 

BRANCHES  OF  THE  VENA  OCCIPITALIS  EXTERNUS 


Vena 
occipitalis 
externus 


Sinus 
longitudinalis 


Sinus 
semicircularis 


Venae  choroideae 

Venae  cutaneae  et  frontales 

Venae  nasales 

Venae  ophthalmias 


f  Sinus 

I    transversus 


Sinus  occipitalis 

Sinus  temporo-sphenoideus 

Venae  cerebellares 

Sinus  petrosus  sphenoideus 


Sinus  petrosus  sphenoideus 
Sinus  temporo-sphenoideus 
Sinus  foraminus  occipitalis 


Retis  mirabile  temporalis 
Sinus  annularis  venosus  basilaris 
Venae  medullares 


Sinus 
venosus 
annularis 
basilaris 


Venae  cerebrales 

Vena  cerebralis  basilaris 


Sinus  venosus  annularis  anterior 


Vena  ophthalmica 

Vena  medullaris  mediana  longitudinalis 


The  vena  cephalica  posterior  (Fig.  62,  No.  B,  8)  is  formed  from 
the  veins  of  the  sinuses  of  the  cranium,  the  brain,  the  vena  auris, 
the  vena  jugularis  prima,  the  vena  carotis,  and  the  vena  occipitalis. 
It  collects  most  of  the  blood  from  the  cranium  and  the  posterior  part 
of  the  head  and  from  the  tongue. 

THE  VENOUS  SINUSES  OF  THE  HEAD 

The  sinus  longitudinalis  (Fig.  62,  A,  10)  extends  from  the  dorsal 
median  line  of  the  internal  occipital  protuberance  to  the  olfactory 


240  ANATOMY   OF   THE   DOMESTIC    FOWL 

nerve.  It  collects  the  blood  from  the  choroidea  of  the  brain  and 
from  the  skin  of  the  frontal  region.  It  receives  laterally  the  veins 
of  the  nose,  the  vena  ophthalmica,  and  the  sinus  transversus. 

The  sinus  occipitalis  (Fig.  62,  No.  A,  4)  forms  the  continuation 
of  the  transverse  sinus.  It  is  located  in  the  posterior  cerebral 
cavity,  and  is  wing-shaped,  extending  both  to  the  right  and  to  the 
left. 

The  sinus  foraminis  occipitalis  a  continuation  of  the  sinus  occip- 
italis, lies  transversely  on  the  ventral  side  of  the  cranial  cavity 
and  rece  ves  the  veins  from  the  medulla  oblongata.  One  branch 
passes  through  the  os  occipitalis  basilare,  and  then  extends  side- 
wise  to  the  foramen  magnum  and  anastomoses  with  the  vena 
occipitalis. 

The  sinus  transversus  (Fig.  62,  No.  A,  6)  extends  in  a  pair  from 
the  internal  occipital  protuberance  between  the  cerebrum,  cere- 
bellum, and  the  corpus  quadrigeminum.  It  receives  vessels  from 
the  upper  surface  of  the  cerebellum.  The  sinus  has  three  branches, 
all  of  which  empty  into  the  sinus  semicircularis. 

The  sinus  semicircularis  extends  along  the  dorsal  petrosal  rim, 
anterior  to  the  inner  ear,  and  from  this  point  backward.  Near  the 
foramen  magnum  it  passes  through  the  os  occipitale  and  empties 
into  the  external  occipital  vein. 

The  vena  occipitalis  externus  extends  near  the  foramen  magnum, 
surrounds  the  basis  occipitalis,  and  receives  the  semicircular  sinus 
and  thorugh  the  semicircular  sinus  the  blood  from  the  sinus  trans- 
versus. 

The  sinus  petrosus  sphenoideus,  passing  in  company  with  the 
occipital  sinus,  extends  from  the  transverse  sinus  to  the  cavity  near 
which  the  trigeminus  lies.  The  sinus  dividing  into  two  branches, 
one  of  these  extends  to  the  hypophysis  and  unites  with  the  basal 
veins  of  the  brain;  the  other  passes  with  the  rete  out  of  the  cranial 
cavity  along  with  a  branch  of  the  trigeminus,  and  communicates 
with  jthe  rete  mirabile  temporale. 

The  sinus  temporo-sphenoideus  (Fig.  62,  No.  A,  5)  extends  for- 
ward and  outward  from  the  transverse  sinus,  and,  between  the 
corpus  quadrigeminum  and  the  cerebrum,  unites  with  the  sinus 
venosus  annularis  basilaris. 

The  sinus  venosus  annularis  basilaris  lies  in  the  region  of  the 
optic  nerve  and  surrounds  the  hypophysis,  forming  a  complete  circle. 
It  receives  small  vessels  from  the  cerebrum,  the  corpora  quadri- 


ANGIOLOGY  241 

gemina,  and  anteriorly  the  longitudinal  basilar  vein  or  vena  basilaris 
media,  of  the  cerebrum,  which  comes  out  of  the  anterior  annular 
venous  sinus.  The  anterior  annular  venous  sinus  surrounds  the  Ease 
of  the  olfactory  nerves.  It  communicates  with  the  sinus  petrosus 
sphenoideus,  which  emerges  from  behind  the  optic  lobe,  the  sinus 
temporo-sphenoideus,  which  emerges  from  in  front  of  the  optic  lobe, 
and  posteriorly  the  median  longitudinal  vein  of  the  medulla  ob- 
longata  or  vena  basilaris.  Laterally  and  anterior  to  the  optic  lobe 
it  receives  the  vena  basilaris  lateralis,  and  also  a  branch  of  the 
vena  ophthalmica. 

The  blood  received  by  the  sinus  annularis  basilaris  comes  from 
the  brain  cavity  through  three  pairs  of  veins,  as  follows:  first,  the 
two  ophthalmic  veins  which  pass  through  the  posterior  orbital  wall 
between  the  olfactory  and  the  optic  nerve;  second,  two  other  bran- 
ches of  the  ophthalmica  which  pass  with  the  optic  nerve;  third,  two 
veins  which  pass  through  a  foramen  by  the  side  of  the  sella  turcica 
to  the  hypophysis  together  with  the  carotis  cerebralis,  and  then 
leave  the  cerebral  cavity  ventrally,  at  which  point  they  are  called 
the  venae  carotes.  These  last  accompany  the  cerebral  artery  back- 
ward, and  pass  through  a  foramen  in  the  base  of  the  cranium. 
Each  one  then  passes  through  the  cranial  wall  close  to  the  external 
auditory  canal,  and  empties  into  another  vein  in  the  posterior  re- 
gion of  the  head. 

The  sinus  fovae  hemispherii  cerebelli  lies  in  the  hollow  between 
the  os  petrosum  and  the  semicircular  canals.  It  receives  blood  from 
the  external  occipital  sinus  and  from  the  cerebellum,  and  empties 
into  the  vena  auris  interna. 

VEINS  OF  THE  BRAIN  CAVITY 

The  vena  auris  interna  passes  through  a  bony  canal  along  the 
outer  rim  of  the  posterior  semicircular  canal  and  then  a  ong  the 
external  semicircular  canal.  It -receives  vessels  from  the  labyrinth, 
and  extends  along  the  posterior  rim  of  the  tympanum  to  the  outer 
ear  canal. 

The  vena  occipitalis  interna,  extending  from  the  sinus  foraminis 
occipitalis,  passes  through  the  side  of  the  atlas  and  divides  near  the 
condyle  into  two  branches.  One  of  these  branches  the  internal 
occipital,  forms  the  root  of  the  vena  vertebralis,  and  the  other 
empties  into  the  vena  occipitalis  externa. 

16 


242  ANATOMY   OF   THE  DOMESTIC  FOWL 

Near  the  outer  and  upper  part  of  the  condyle  it  forms  two  large 
veins  and  collects  the  blood  from  the  vena  occipitalis  media.  These 
veins  collect  the  blood  from  the  rectus  capitis  anticus,  and  communi- 
cate with  the  vena  cephalica  anterior. 

The  vena  occipitalis  externa,  sometimes  called  the  vena  occip- 
italis collateralis,  extends  from  the  vena  auris,  and  receives  vessels 
from  the  neck  region.  It  receives  on  the  side  of  the  occipito- 
atloid  joint  the  vena  occipitalis  interna.  The  vena  occipitalis 
externa  forms  a  junction  with  the  vena  vertebralis  emptying 
into  the  transverse  vein. 


THE  VEINS   OF  THE  NECK 

BRANCHES  OF  THE  VENA  JUGULARIS 

The  trunks  of  the  vena  jugularis  or  vena  cephalica  communis 
pass  subcutaneously  on  both  sides  near  the  trachea  and  the  esopha- 
gus. Near  the  height  of  the  thyroid  gland  they  almost  touch  the 
carotid  artery.  They  then  cross,  dorsalward,  the  trunk  of  the  sub- 
clavian  artery,  and  in  their  course  receive  the  vertebral  vein  and 
unite  with  the  subclavian  vein  toward  the  side  of  the  vena  brachio- 
cephalica.  The  union  on  the  right  side  lies  to  the  right  of  the 
anterior  aorta,  and  the  union  on  the  left  side  lies  to  the  left  of  the 
pulmonary  artery. 

The  jugular  vein  (Fig.  18,  No.  4)  receives  in  its  course  the  follow- 
ing veins: 

The  venae  linguales  (Fig.  62,  No.  B,  7),  which  at  times  empty 
into  the  vena  cephalica  posterior. 

The  vena  occipito-collares,  which  arises  on  the  ventral  side  from 
the  muscles  of  the  neck  and  the  vertebrae;  empties  into  the  vena 
occipitalis  lateralis  and  also  communicates  with  the  vena  jugularis 
by  anastomoses. 

The  venae  ascendentes  laterales,  which  collect  blood  from  the 
lateral  sides  of  the  neck. 

The  venae  colli  cutineae,  which  enter  the  jugular  vein  laterally. 
The  upper  branches  are  directed  crosswise,  and  are  shorter  than  the 
lower  ones.  The  lower  branches  are  located  near  the  thorax,  are 
directed  upward,  and  anastomose  by  fine  terminal  twigs.  Plexuses 
are  frequently  formed  in  the  inner  side  of  the  skin  of  the  neck. 


ANGIOLOGY 


243 


BRANCHES  OF  THE  VENA  SUBCLAVIA 


Truncus  venae 
subclavise 


Truncus  venae 
axillaris 


I  Vena  profunda  ulnaris 

Vena  brachialis   |  Vena  profunda  radialis 

I  Vena  profunda  humeri 

Vena  basilica  or  cutinea  ulnaris 


f  Vena  cutinea  abdomino-pectoralis 
Vena  pectoris       Vena  infrascapularis  anterior 
externa  I  Vena  thoracica  externa 

Vena  coracoidea 
Vena  sternalis 


The  venae  esophageae  are  numerous  smaller  veins  formed  in 
closely  woven  plexuses  in  the  region  of  the  esophagus  along  the 
neck.  Some  pass  upward  and  some  downward. 

The  venae  tracheales  are  located  on  the  supero-lateral  side  of  the 
trachea  and  along  the  edge  of  the  lateral  tracheal  muscle.  They 
have  numerous  anastomoses  transversely  with  the  longitudinal 
vein  of  the  cervical  region,  anteriorly  with  the  vena  lingualis,  and 
on  the  left  side  with  the  left  jugular  vein. 

The  vena  subscapularis  passes  along  the  median  line  of  the  scapula 
to  the  side  of  the  jugular  vein,  and  anastomoses  with  the  vertebral 
vein. 

The  venae  glandularum  thyroidearum  are  several  small,  short 
veins  coming  from  the  thyroid  gland. 

The  vena  vertebralis,  originating  near  the  atlas,  is  a  continuation 
of  the  internal  occipita1  vein.  The  internal  occipital  vein  receives 
the  bulk  of  the  blood  from  the  brain  and  communicates  with  the 
lateral  veins  of  the  cervical  region  and  collects  blood  from  the  cer- 
vical vertebra.  The  vertebral  vein  accompanies  the  vertebral 
artery  and  the  deep  sympathetic  nerve  trunk  in  the  vertebral  canal. 
The  vein  either  leaves  this  canal  with  the  vertebral  artery  at  a  point 
near  the  last  two  vertebral  nerve  trunks  of  the  brachial  plexus,  or 
it  leaves  the  canal  one  vertebra  in  front  of  the  vertebral  artery. 


THE  VEINS  OF  THE  DORSAL  REGION 

The  vena  vertebralis  lateralis  dorsalis  collects  blood  from  the 
cervical  vertebrae,  from  the  dorsal  vertebrae,  and  from  the  inter- 
costal region. 


244  ANATOMY   OF    THE   DOMESTIC   FOWL 

The  blood  from  the  neural  canal,  including  the  spinal  cord,  is 
collected  in  one  long  vein  extending  from  the  head  to  the  tail  on 
the  upper  side  of  the  cord.  This  vein  has  sinus-like  expansions. 
Between  each  two  vertebrae  it  anastomoses  with  the  vertebral  vein 
on  each  side.  In  the  lumbo-sacral  region  these  anastomotic  branches 
empty  into  the  hypogastric  veins. 

The  vena  intercostalis  is  formed  in  the  costal  region  and  anas- 
tomoses with  the  vein  extending  longitudinally  between  the 
capitulum  and  the  tuberculum  of  the  rib. 

The  vena  vertebralis  posterior  at  the  height  of  the  first  and  the 
second  dorsal  vertebras,  empties  into  the  main  trunk  of  the  verte- 
bral vein.  Its  lower  roots  come  out  near  the  side  of  the  kidney, 
and  unite,  forming  a  large  ascending  trunk  uniting  with  the  vena 
vertebralis  anterior  forming  one  large  trunk,  which  extends  into  the 
chest  cavity. 

The  posterior  vertebral  vein  also  receives  a  large  vein  from  the  skin 
of  the  outer  tarsal  region  and  a  few  vessels  from  the  muscles  of 
the  outer  abdominal  and  the  outer  costal  region,  from  the  skin, 
from  the  pectoralis  muscles,  and  from  the  shoulder  region. 

VEINS  OF  THE  THORAX 

BRANCHES  OF  THE  VENA  SUBCLAVIA 

The  vena  thoracica  externa  (Fig.  73,  No.  2)  is  made  up  of  veins 
mainly  from  the  pectoral  group  of  muscles.  The  posterior  branch 
anastomoses  with  the  vena  cutinea.  Its  anterior  branch  is  made  up 
mainly  of  branches  from  the  furcular  region.  It  empties  into  the 
vena  pectoralis  externa  and  the  vena  pectoralis  externa  empties  into 
the  vena  subclavia. 

The  vena  coracoidea  comes  out  of  the  region  of  the  shoulder- 
joint,  passes  downward  along  the  inner  surface  of  the  coracoid, 
and  receives  small  branches  from  the  walls  of  the  arteria  brachia 
cephalica  and  from  the  pericardium. 

The  vena  sternalis  (Fig.  73,  No.  i)  is  made  up  of  two  branches. 
The  outer  branch  comes  from  the  muscles  of  the  subclavian  region 
passes  over  the  cristi  sterni,  medially,  to  the  sterno-coracoid  joint 
and  into  the  breast  cavity,  where  it  receives  the  inner  branch, 
which  drains  the  inner  surface  of  the  breast-bone. 

The  vena  thoracica  interna  empties  into  the  vena  cava  anterior. 
It  extends  from  the  abdominal  muscles  where  it  communicates  with 


ANGIOLOGY  245 

the  epigastric  vein.  It  then  passes  on  the  inner  side  of  the  thoracic 
cavity  close  to  the  breast-bone  and  receives  many  intercostal  veins. 
The  vena  cava  sinistra  receives  first,  the  -vena  proventricularis 
communis,  which  collects  the  blood  from  the  walls  of  the  proven- 
triculus,  and  second,  the  vena  coronaria  cardis  magna.  This  latter 
vein  originates  close  to  the  apex  of  the  heart  and  collects  blood 
principally  from  the  walls  of  the  left  ventricle.  It  connects  in 
the  left  sulcus  transversus  with  the  vena  cardis  superior  and  ends 
at  the  base  of  the  left  upper  vena  cava.  Its  exit  is  not  guarded 
by  a  valve.  The  veins  of  the  right  ventricle  are  partly  on  the 
surface.  They  collect  blood  along  the  sulcus  transversus  dexter 
and  enter  directly  into  the  right  ventricle.  The  veins  of  the  front 
part  of  the  heart  are  small.  They  collect  behind  the  sulcus  coro- 
nalis  and  end  either  directly  into  the  right  auricle  or  into  the  vena 
cardis  magna. 

VEINS  OF  THE  FORE  LIMB 

The  vena  radialis  profunda  accompanies  the  radial  artery  on  the 
dorsal  anterior  rim  of  the  index -finger  and  passes,  on  the  dorsal 
side,  over  the  carpal  region.  It  passes  through  the  interosseous 
ligament  between  the  ulna  and  the  radius,  and  reaches  the  ventral 
surface  of  the  arm.  At  this  point  it  passes  upward  and  anastomoses 
with  the  vena  ulnaris.  It  collects  the  blood  from  the  skin  of  the 
anterior  wing  region  and  the  flexor  muscles  of  the  anterior  arm.  It 
empties  into  the  vena  brachialis. 

The  vena  humeri  profunda  (Fig.  68,  No.  i)  emerges  at  the  height 
of  the  elbow,  and  collects  blood  from  the  skin  of  the  dorsal  surface 
of  the  wing.  It  also  receives  veins  from  the  muscles  of  the  posterior 
side  of  the  upper  arm.  It  passes  subcutaneously  and  dorsally  over 
the  dorsal  portion  of  the  humerus  in  company  with  the  external 
radial  muscle  and  passes  with  it  around  the  external  part  of  the  hu- 
merus between  the  long  and  short  heads  of  the  triceps.  It  takes  a 
diagonal  course  to  the  shoulder  cavity  and  at  that  point  empties  into 
the  brachial  trunk. 

The  profundus  ulnaris  originates  at  the  volar  surface  of  the  hand, 
proceeds  in  company  with  the  ulnar  artery,  and  sends  on  the  base  of 
the  hand  small  anastomotic  veins  to  the  vena  cutanea  ulnaris  or 
basilica.  It  passes  along  the  anterior  arm  and  between  the  flexor 
carpi  ulnaris  and  the  pronator  profundus  muscle  to  the  elbow-joint. 
On  the  median  surface  of  the  biceps  it  passes  upward  and  anastomo- 


246 


ANATOMY   OF    THE   DOMESTIC   FOWL 


ses  with  the  radial  vein.  The  ulnar  vein,  in  the  region  of  the  elbow- 
joint,  receives  a  large  lateral  branch  which  extends  around  the  end 
tendon  of  the  biceps  and  anastomoses  above  with  the  vena  basilica. 

The  vena  basilica  or  cutanea  ulnaris  is  a  long  vein  which  originates 
from  the  subcutaneous  dorsal  surface  of  the  index-finger.  Near  the 
base  of  the  hand  it  receives  an  anastomosing  branch  from  the  vena 
radialis  and  the  vena  ulnaris,  and  then  passes  upward  along  the 
posterior  rim  of  the  ulna.  It  receives  numerous  branches  from  the 
roots  of  the  flight  feathers.  It  crosses  below  the  elbow-joint  and 
reaches  the  volar  surface  of  the  arm.  It  receives  a  large  branch 
from  the  ulnar  vein,  and  then,  passing  in  a  diagonal  and  median 
direction  to  the  triceps,  extends  to  the  shoulder  cavity  where  it 
empties  into  the  axillary  vein. 

.  The  outer  breast  veins  unite  forming  a  trunk  which  crosses  ven- 
tral! y  to  the  subclavian  artery,  and  empties  into  the  subclavian 
vein. 

The  vena  cutanea  abdomino-pectoralis  collects  the  blood  from  a 
large  skin  area  of  the  abdomen,  the  upper  thigh,  the  breast,  and  the 
intercostal  region.  In  the  skin  of  the  abdomen  it  forms  a  network. 

BRANCHES  OF  THE  ILIACS 

Vena  metatarsalis      f  Vena  metatarsalis 
Vena  interna  or  magna     I    plantaris  profunda 


Vena 
iliaca 
externa 


Vena 
poplitealis 


Vena 
cruralis 


tibialis 
postica 


Vena 
tibialis 
antica 


Vena  tibialis  antica 
Vena  metatarsalis 
externa 


Venae  metatarsales 


Vena  metatarsalis  dorsalis  profunda 
Vena  metatarsalis  dorsalis  interna 
Vena  peronealis 


Vena  cutanea  cruralis 
.  Venae  su  rales 

Vena  cutanea  abdominalis  femoralis 
Vena  femoralis  interna  profunda 
Vena  femoralis  anterior 
Vena  epigastrica 


The  main  trunk  passes  in  the  median  abdominal  line  forward  and 
then  upward,  along  the  outer  edge  of  the  pectoralis  major,  over  the 
first  sternal  rib;  receives  blood  from  the  infrascapular  vein,  and  emp- 
ties into  the  pectoralis  externa. 

The  vena  brachialis  is  located  in  the  middle  of  the  humerus  and 


ANGIOLOGY 


247 


the  triceps  muscle.  It  is  formed  by  the  vena  ulnaris,  and  the  vena 
radialis.  It  passes  with  the  median  nerve  and  the  brachial  artery 
over  the  inner  surface  of  the  humeral  joint.  Posterior  to  the 
humeral  head  it  receives  the  vena  profunda  humeri.  At~the 
shoulder  cavity  it  receives  the  vena  cutanea  ulnaris  or  vena 
basilica. 

The  trunk  of  the  axillary  vein  is  very  short  and  is  formed  by  the 
veins  of  the  shoulder  and  the  wing.  The  deeper  wing  veins  accom- 
pany the  large  arterial  and  the  nerve  trunks. 

BRANCHES  OF  THE  VENA  ILIACA  INTERNA 

Vena  interver-tebralis  lumbalis 


Vena  iliaca 
interna  or 
vena  hy- 
pogastrica 


Pars  truncalis 


Pars  caudalis 


Pars  renalis 


Vena  renalis  magna 

Vena    hypogastrica    caudalis    si- 

nistra 

Vena  renalis        Vena  hypogastrica  caudalis  dex- 
tra 

Vena  portalis 
Vena  coccygea     Vena  cutanea  et  pudenda 

Vena  coccygea  mesenterica 
Vena  cutanea  pubica 
Vena  cutanea  caudalis 
Vena  pudenda  ( Vena  spermatica 
Vena  caudalis  muscularis 
Venae  sacrales 

Venae  intervertebrales  sacralis  ( Venae  renales 
Venae  renales 
Vena  ischiadica 
Vena  obturatoria 
Vena  sup.ra-renalis  externa  ( Azygos  sacralis 


THE  POSTERIOR  VENA  CAVA 

The  posterior  vena  cava  (Fig.  63,  No.  18;  Fig.  70,  No.  8)  has  its 
origin  in  the  posterior  half  of  the  body  of  the  bird,  somewhat  to 
the  right  of  the  posterior  aorta,  near  the  anterior  lobe  of  the  kidney, 
by  the  union  of  the  right  and  the  left  vena  iliaca  communis.  It 
receives  the  blood  from  all  of  the  posterior  half  of  the  body  including 
the  posterior  limbs,  of  the  visceral  organs,  of  the  abdominal  and  the 
pelvic  cavity.  The  posterior  vena  cava  passes  dorsally  through 
the  right  lobe  of  the  liver  and  through  the  diaphragm  and  ends  in  a 
short,  broad  trunk  on  the  posterior  dorsal  side  of  the  right  auricle 
of  the  heart.  Its  opening  into  the  heart  is  guarded  by  two  half- 


248 


ANATOMY    OF    THE   DOMESTIC   FOWL 


moon  shaped  valves.  The  basal  part  of  the  trunk  reaches  from  the 
right  auricle  o  the  heart  to  the  upper  anterior  rim  of  the  liver  where 
it  receives  three  large  trunks,  first,  the  right  and  second,  the  left 
vena  portalis  hepatica  magna,  and  third,  smaller  vessels  from  the 
liver  substance. 

THE  VEINS  OF  THE  POSTERIOR  EXTREMITY 

In  the  skin  region  on  the  inner  sides  of  the  toes  near  their  bases 
the  small  veins  collect  into  five  metatarsal  veins.  The  largest  vein 
collects  the  blood  from  the  first,  the  second,  and  the  third  toe, 
passes  up  the  tarsus  and  is  called  the  vena  metatarsalis  interna,  or 
vena  magna  (Fig.  65,  No.  7).  It  is  located  just  beneath  the  skin 
on  the  inner  surface  of  the  metatarsal  bone.  It  passes  in  a  circle, 
around  the  condyle  of  the  tibia  and  becomes  the  vena  tibialis  postica 
(Fig.  65,  No.  3  and  8).  The  vena  tibialis  postica  passes  under  the 
tendon  Achillis  and  the  tendon  of  the  flexor  digitorum  brevis,  lies 


Vena  cava 
posterior 


Vena 
portalis 
dextra 


BRANCHES  OF  THE  VENA  CAVA  POSTERIOR 

Vena  ovariana 

Venae  testiculae 

Vena  proventricularis  communis 

Vena  suprarenalis  revehentis 

Vena  portalis  magna  sinistra 

Vena  portalis  magna  dextra 

Venae  innominatae 

Venae  hepaticae 

Vena  cardis  coronaria  magna 

Vena  proventricularis  inferior 

Vena  iliaca  interna    (  Vena  hypogastrica 

Vena  iliaca  externa    I  Vena  renalis 

Vena  supra-renalis  externa 
Vena  iliaca     Vena  ischiadica 
communis     Vena  renalis 

Vena  intervertebralis  lumbalis 

Vena  renalis  magna 


Vena  coccygo-mesenterica 
Vena  mesenterica  anterior 


Vena  mesenterica  communis 

Vena  pancreatico-duodenalis 

.    (  Vena  proventricularis 
Vena  proventricularis  lienahs     _,        r  .     . 

I  Vena  splenica 


Vena  coccygo-mesenterica  [  Vena  hemorrhoidalis 


ANGIOLOGY  249 

subcutaneously  upon  the  latter,  and  reaching  the  knee-joint  crosses 
over  the  upper  surface  of  the  ischiadic  nerve  and  becomes  the 
vena  poplitealis,  at  which  point  it  receives  the  vena  tibialis  antica. 

On  the  dorsal  side  of  the  metatarsus  are  two  veins.  The  vena 
metatarsalis  dorsalis  profunda  (Fig.  65,  No.  n),  which  extends  under 
the  tendon  of  the  extensors  of  the  toes,  along  with  the  artery  and  the 
nerve.  It  collects  the  blood  from  the  third  and  the  fourth  toe  and  in 
the  middle  of  the  metatarsus  receives  the  vena  metatarsalis 
dorsalis  interna  (Fig.  65,  No.  4),  which  connects  the  vena  metatar- 
salis dorsalis  profunda  and  the  vena  magna.  The  two  dorsal  veins 
anastomose  with  the  vena  magna,  at  the  intertarsal  joint.  They 
pass  transversely  under  the  ligament  and  form  the  main  trunk  of  the 
vena  tibialis  antica  which  lies  close  to  the  anterior  surface  of  the 
tibia.  Near  this  point  there  is  formed  a  plexus  of  veins  which 
again  form  a  trunk  and  communicates  with  the  vena  peronealis  and 
enters  between  the  tibia  and  fibula  with  the  tibialis  antica.  It 
extends  along  the  flexure  of  the  knee  and  the  posterior  part  of  the 
lower  thigh. 

The  vena  metatarsalis  externa  passes  subcutaneously  on  the 
outside  of  the  fourth  toe  and  the  metatarsus,  and  above  the 
intertarsal  point  joins  the  tibialis  postica. 

The  vena  metatarsalis  plantaris  profunda  (Fig.  65,  No.  5)  lies 
on  the  ventral  side  of  the  foot  and  forms  several  anastomosing 
arches  with  the  other  veins  of  the  toes.  Below  the  intertarsal  joint 
it  enters  the  vena  metatarsalis  magna  (Fig.  65,  No.  9). 

The  vena  cutanea  cruralis  (Fig.  69,  No.  7)  originates  at  the  height 
of  the  tarsal  region  and  passes  subcutaneously  on  the  outer  posterior 
surface  of  the  lower  thigh  region  to  the  vena  poplitealis. 

The  venae  surales  or  inferior  muscular  branches  of  the  vena  poplit- 
ealis consist  of  many  veins.  One  branch  comes  from  the  region  of  the 
shank  and  from  the  gastrocnemius  muscle;  another  as  a  main  branch 
from  the  posterior  surface  of  the  lower  thigh;  and  a  third  from  the 
outer  surface  of  the  muscles  and  skin  of  the  upper  thigh.  The  three 
branches  together  with  the  anterior  and  posterior  tibial  (Fig.  69, 
No.  2)  unite  at  the  flexure  of  the  knee  forming  the  vena  poplitealis 
(Fig.  69,  No.  i). 

In  the  region  of  the  upper  thigh,  between  the  knee  and  the  ab- 
dominal cavity,  the  following  four  veins  form  the  vena  cruralis: 
(Fig.  66,  No.  6;  Fig.  69,  No.  5)  First,  the  vena  cutanea  abdominalis 
femoralis  (Fig.  69,  No.  6)  which  comes  out  of  the  side  of  theabdomi- 


250  ANATOMY   OF   THE   DOMESTIC   FOWL 

nal  wall,  draining  the  skin  of  the  inner  surface  of  the  upper  portion 
of  the  thigh,  the  adductor  muscles,  and  the  region  of  the  abdominal 
and  the  breast  border.  It  crosses  the  ischiadic  artery  in  a  diagonal 
direction,  and  enters  the  vena  cruralis  in  the  middle  of  the  crural 
region. 

Second,  the  vena  femoralis  interna  profunda  (Fig.  69,  No.  3)  forms 
a  communication  between  the  end  of  the  suralis  near  the  knee.  It 
lies  on  the  median  portion  of  the  flexor  cruris  internus  muscle. 

Third,  the  vena  femoralis  anterior  (Fig.  69,  No.  4)  is  formed 
from  branches  from  the  sartorius  and  adjacent  structures,  and 
anteriorly  empties  into  the  crural  vein  near  where  the  latter  enters 
the  abdominal  cavity. 

Fourth,  the  vena  epigastrica  (Fig.  70,  No.  33)  is  formed  by  branches 
from  the  abdominal  wall  and  branches  from  the  walls  of  the  abdomi- 
nal air-sacs.  It  passes  along  the  median  surface  of  the  os  pubis 
and  ends  into  the  vena  cruralis  near  the  spine  of  the  ilio-pubica  or  at 
a  point  where  these  join  with  the  vena  hypogastrica. 


VEINS  OF  THE  CAUDAL  REGION  AND  OF  THE  PELVIC  CAVITY 

The  vena  iliaca  interna  or  the  vena  hypogastrica  (Fig.  70,  No.  22) 
collects  most  of  the  blood  from  the  tail.  The  vena  iliaca  interna 
collects  most  of  the  blood  from  the  pelvic  cavity,  and  the  adjacent 
intestines.  It  unites  with  the  vena  iliaca  externa  (Fig.  70,  No.  27) 
and  receives  the  vena  renalis  magna  and  forms  the  trunk  of  the 
vena  iliaca  communis  (Fig.  70,  No.  26). 

The  vena  coccygea  originates  between  the  coccygeal  vertebrae, 
and  coUects  the  blood  from  the  region  of  the  tail,  including  the  tail 
feathers,  the  tail  muscles,  the  tail  gland,  and  the  skin  of  the  region. 
These  small  collecting  vessels  form  a  trunk  on  each  side  of  the  coccyx. 
The  right  and  the  left  pass  laterally,  each  one  taking  up  a  vena 
cutanea  et  pudenda,  and  frequently  anastomosing  with  the  vessels 
on  the  other  side.  These  often  unite  into  one  vessel.  Both  trunks 
are  connected  by  a  transverse,  or  anastomotic,  vessel.  At  this 
anastomosis  there  empty  into  it  the  vena  coccygea  mesenterica  and 
the  vena  portalis.  There  also  communicate  at  this  point  the  right 
and  the  left  hypogastrica  caudalis.  In  its  course  it  is  partly  im- 
bedded in  the  kidney  and  passes  anteriorly  to  the  vena  iliaca  com- 
munis. This  circle  is  called  the  arcus  hypogastricus.  Thus  the 


ANGIOLOGY  251 

veins  of  the  abdominal  cavity  have  many  anastomoses  forming 
many  arcs,  making  possible  two  outlets  for  the  blood. 

The  azygos  sacralis  empties  into  the  arcus  at  about  its  middle. 
From  here  it  extends  forward  to  the  inside  and  under  the  kidney  and 
empties  into  the  vena  suprarenalis  externa. 

The  vena  cutanea  pubica  originates  on  the  lower  portion  of  the 
abdomen,  collects  the  blood  from  the  muscles  of  the  distal  part  of 
the  ischium,  and  enters  the  pelvic  cavity  between  the  ischium  and 
the  ilium.  It  joins  with  the  vena  cutanea  caudalis. 

The  vena  cutanea  caudalis  originates  from  branches  which  drain 
the  skin  and  other  parts  of  the  ventral  coccygeal  region.  The  vena 
cutanea  pubica  also  communicates  with  the  vena  caudalis  muscularis 
and  with  the  vena  pudenda,  thus  forming  the  caudal  trunk  of  the 
vena  hypogastrica. 

The  vena  pudenda  originates  in  the  walls  of  the  cloaca  in  the 
region  of  the  generative  organs. 

A  small  vena  spermatica  accompanies  the  lower  end  of  the  vas 
deferens  and  the  ureter,  and  empties  medially  into  the  vena  pudenda. 

The  pars  renalis  of  the  vena  hypogastrica  extends  from  the  middle 
of  the  arcus  to  the  union  of  the  vena  hypogastrica  and  the  vena 
cruralis. 

The  vena  hypogastrica  communicates  with  the  pars  renalis. 
The  vessels  that  empty  into  the  pars  renalis  are  as  follows: 

The  venae  sacrales  collect  blood  from  the  dorsal  wall  of  the 
abdominal  cavity  and  enter  the  pelvis  through  the  foramen  sacralis. 
They  pass  between  the  pelvic  wall  and  kidney,  and  at  times  pass 
through  the  kidney  tissue.  They  empty  into  the  pars  renalis  of  the 
hypogastric  arch. 

The  venae  intervertebrales  sacrales  (Fig.  72,  No.  2)  originate 
in  the  region  of  the  roots  of  the  plexus  of  sacral  nerves  and  pass 
through  the  kidney  substance  or  on  the  dorsal  surface  and  empty  into 
the  pars  renalis. 

The  venae  renales  (Fig.  72,  No.  i)  are  very  numerous  and  origi- 
nate in  the  kidney  substance,  forming  two  main  and  several  minor 
branches,  which  pass  posteriorly,  and  empty  partly  into  the  vena 
hypogastrica,  partly  into  the  vena  renalis  magna,  and  also  into  the 
vena  intervertebralis;  other  branches  empty  into  the  trunk  of  the 
iliaca  communis. 

The  vena  suprarenalis  externa  (Fig.  70,  No.  30)  is  located  near 
the  anterior  rim  of  the  kidney  and  is  connected  with  the  vena 


252  ANATOMY    OF    THE   DOMESTIC   FOWL 

hypogastrica.  It  also  receives  on  the  medial  side,  short  branches 
which  come  out  of  the  upper  kidney  surface  and  sacral  vertebrae. 

The  vena  ischiatica  originates  by  the  union  of  several  venous 
branches  which  come  from  the  muscles  of  the  pelvis  and  upper 
thigh  region.  The  ischiatic  vein  enters  the  pelvic  cavity  along 
with  the  ischiatic  nerve  and  artery,  and  communicates  with  the 
vena  hypogastrica  at  about  the  level  of  the  anterior  lobe  of  the 
kidney.  It  is  always  smaller  than  the  vena  cruralis. 

The  vena  obturatoria  originates  mainly  from  vessels  from  the 
obturator  muscles.  It  enters  the  pelvic  cavity  through  the  obtura- 
tor foramen.  Another  branch  is  sometimes  found  which  comes 
out  of  the  inner  surface  of  the  peritoneum  which  covers  the  obturator 
muscles  and  the  walls  of  the  abdominal  air-sacs  and  empties 
between  the  vena  ischiatica  and  the  vena  vertebralis  into  the 
vena  hypogastrica. 

VEINS  OF  THE  TRUNCUS  VENA  ILIACA  COMMUNIS 

The  vena  intervertebralis  lumbalis,  which  comes  out  of  the 
lumbar  region,  the  spinal  canal,  the  lumbo-sacral  nerve  plexus,  and 
several  small  venous  branches  from  the  lobes  of  the  kidney.  It 
passes  dorsalward  through  the  kidney  and  empties  into  the  iliac 
vein.  There  are  also  communications  with  the  vena  interverte- 
bralis thoracica. 

The  vena  renalis  magna  (Fig.  64,  No.  47)  forms  the  main  descend- 
ing vein  to  the  middle  and  posterior  lobes  of  the  kidney.  It  lies 
ventrally  and  mesially  on  the  middle  lobe  and  partly  on  the  inner 
part  of  the  posterior  lobe.  It  sometimes  has  on  each  side  two  main 
trunks.  The  vein  receives  some  small  vessels  out  of  the  anterior 
kidney  lobe,  also  other  small  veins  from  that  part  of  the  peritoneum 
which  covers  the  kidney,  from  the  rectum  and  finally  small  veins 
from  the  ureter. 

VISCERAL  VEINS  OF  THE  POSTERIOR  VENA  CAVA 

The  venae  testiculae,  or  the  vena  ovariana  drain  the  blood  from 
the  testicles  of  the  male  and  ovary  of  the  female.  The  size  of  these 
veins  change  with  the  enlargement  of  the  testes  or  of  the  ovary 
during  reproductive  activity. 

The  venae  supra-renales  revehentes  are  short,  thick  trunks  com- 
ing from  the  adrenal  glands.  The  left  empties  into  the  left  side  of 


ANGIOLOGY  253 

the  posterior  vena  cava  and  the  right  into  the  right  dorsal  side. 
These  receive  veins  from  the  testicles  in  the  male  and  from  the  ovary 
in  the  female. 

The  vena  proventricularis  inferior  drains  the  stomach  wall.  One 
branch  of  this  vein  enters  the  left  side  of  the  posterior  vena  cava; 
the  other  enters  the  vena  proventricularis  communis,  which  in  turn 
empties  into  the  trunk  of  the  anterior  vena  cava  sinistra. 

The  venae  hepaticse  consist  of  one  large  and  several  small 
veins  from  each  lobe  of  the  liver,  and  empty  into  the  posterior 
vena  cava. 

Some  small  vessels  come  from  the  pericardium  and  the  peritoneal 
covering  of  the  liver,  and  pass  in  the  mediastinum  to  the  trunk  of 
the  posterior  vena  cava. 

In  the  region  of  the  vena  portalis: 

The  liver  receives  almost  all  the  blood  from  the  stomach,  the 
intestines,  the  pancreatic  gland,  the  spleen,  partly  from  the  liver 
itself,  and  partly  from  the  abdominal  air-sacs.  This  blood  enters 
into  the  liver  through  the  vena  portalis  dextra,  the  vena  portalis 
sinistra,  and  the  vena  portalis  propria. 

In  both  lobes  of  the  liver  these  veins  divide  into  numerous  small 
branches  and  collect  again  into  two  large  short  trunks,  the  vena 
hepatica  magna  dextra  (Fig.  70,  No.  23),  coming  out  of  the  right 
lobe  of  the  liver  and  the  vena  hepatica  magna  sinistra  (Fig.  70,  No. 
24)  coming  out  of  the  left  lobe.  These  two  vessels  empty  inferiorly 
into  the  posterior  vena  cava. 

The  vena  portalis  dextra  receives  the  blood  from  the  vena  mesen- 
terica  communis. 

The  vena  mesenterica  communis  (Fig.  64,  No.  36)  receives  the 
blood  from  the  vena  coccygo-mesenterica  (Fig.  70,  No.  28)  which 
comes  from  the  arcus  hypogastricus  and  receives  the  vena  hemor- 
rhoidalis  (Fig.  64,  No.  37).  This  drains  the  cloaca  and  the  bursa  of 
Fabricius,  and  it  also  receives  veins  from  the  rectum  and  from  the 
base  of  the  caeca. 

The  vena  mesenterica  anterior  (Fig.  71,  No.  3)  accompanies  the 
anterior  mesenteric  artery,  and  collects  the  blood  from  numerous 
vessels  from  the  small  intestine. 

The  vena  pancreatico-duodenalis  (Fig.  64,  No.  38)  comes  out  of 
the  duodenum  and  the  pancreas,  along  the  right  side  of  the  stomach 
and  along  both  caeca. 

The  vena  proventriculo-lienalis  (Fig.  64,  No.  39)  comes  out  of 


254  ANATOMY  OF   THE  DOMESTIC  FOWL 

the  dorsal  side  of  the  proventriculus  on  the  left  side  of  the  gizzard, 
passes  along  the  hilus  of  the  spleen,  and  takes  up  several  splenic 
veins. 

The  vena  portalis  dextra  (Fig.  64,  No.  40;  Fig.  71,  No.  4)  receives 
a  vein  near  the  base  of  the  gall-bladder.  This  branch  enters  the 
right  lobe  of  the  liver  and  unites  with  the  vena  portalis  sinistra. 

The  vena  portalis  sinistra  (Fig.  71,  No.  5)  enters  the  left  lobe  of 
the  liver  and  there  forms  a  sinus.  It  receives  vessels  which  come 
from  the  muscles  of  the  gizzard,  the  inferior  vena  proventricularis, 
and  from  the  pro  ventricular  wall. 

The  vena  portalis  propria  receives  small  veins  which  come  out  of 
the  walls  of  the  abdominal  air-sacs  and  from  the  fat  of  the  abdominal 
walls. 

The  vena  umbilicalis  originates  in  the  umbilical  region  and  empties 
into  the  vena  hepatica  magna  sinistra  at  a  point  where  it  comes  out 
of  the  liver  (Fig.  70,  No.  29).  This  is  the  remains  of  an  embryonal 
vein  which  collected  all  the  blood  of  the  yolk  sac,  passed  on  the  left 
side  of  the  large  intestine  to  the  body,  took  up  the  vena  mesenterica 
and  ended  as  the  vena  umphalo-mesenterica. 

THE  LYMPHATIC  SYSTEM 

The  peculiarity  of  the  lymph  vessels  is  that  they  are  associated 
with  organs  in  which  lymph  cells  are  formed. 

The  lymphatic  system  consists  of  the  lymph  vessels  and  the  cell- 
forming  organs.  In  some  instances  the  cell-producing  organs  are 
lymph  follicles  and  in  others  lymph  glands.  For  the  most  part  the 
glands  are  replaced  by  plexuses  which  in  many  places  surround  the 
blood-vessels. 

The  lymph  of  birds  is  similar  to  that  of  mammals.  The  larger 
lymph  vessels  are  similar  to  the  veins,  although  the  walls  are  always 
thinner.  Its  tunica  intima  is  rich  in  elastic  fibers  and  has  a  layer 
of  endothelial  cells  on  the  inner  side.  The  tunica  media  is  formed 
of  rings  of  smooth  muscle  fibers.  The  adventitia  is  composed  of 
loose  connective  tissue. 

The  lymph  vessels  frequently  form  plexuses.  The  large  lymph 
trunks  follow  the  course  of  the  larger  blood-vessels,  and  frequently 
surround  the  arteries.  All  the  lymph  vessels  of  the  body,  exclusive 
of  the  lymph  of  the  caudal  region,  form  into  a  large  trunk  which 
originates  on  both  sides  of  the  celiaca  communis  and  passes  upward 


ANGIOLOGY  255 

along  the  side  of  the  abdominal  aorta,  reaching  a  point  anterior 
to  the  celiaca.  By  receiving  many  vessels  in  this  region  it  forms  a 
plexus  around  the  aorta,  and  finally  divides  into  two  vessels,  the 
right  and  the  left,  ducti  thoracici. 

The  lymph  vessels  of  the  left  side  of  the  head,  the  neck,  and  the 
lung,  and  the  left  wing,  and  also  lymph  vessels  of  the  proventriculus 
and  the  throat  enter  into  the  left  ductus  thoracicus.  They  accom- 
pany the  jugular  vein  and  are  closely  associated  with  the  thyroid 
gland. 

The  right  thoracic  duct  receives  the  lymph  veins  from  the  right 
cervical  lymph  vein,  and  the  right  side  of  the  head,  the  neck,  the 
lung,  and  from  the  right  wing. 

After  the  right  cervical  lymph  vein  has  passed  through  the  right 
thyroid  gland,  it  divides  into  two  branches,  one  branch  emptying 
into  the  right  thoracic  duct  and  the  other  into  the  vena  cava  dextra. 

The  lymph  vessels  of  the  liver,  the  stomach,  the  pancreas,  and 
the  duodenum  enter  near  the  root  of  the  arteria  celiaca  into  the 
large  lymph  trunk.  The  lymph  vessels  of  the  remainder  of  the 
intestines,  of  the  kidney,  and  of  the  generative  organs  empty  farther 
caudally. 

The  lymph  vessels  of  the  intestines  take  up  the  emulsified  fat. 
This  emulsion  in  birds  is  colorless.  The  vessels  pass  upward  along 
the  mesenteric  arteries.  There  are  no  mesenteric  glands.  These 
vessels  form  a  plexus  around  the  arteria  celiaca.  The  lymph  vessels 
of  the  posterior  extremities  accompany  the  artery,  especially  the 
anterior  iliaca  externa,  and  empty  into  the  thoracic  duct  at  the 
point  of  the  anterior  iliaco-communis. 

The  lymph  vessels  in  birds  are  numerous.  The  lymph  glands  are 
few.  They  are  only  visibly  found  in  the  anterior  breast  and  the  neck 
region,  and  sometimes  in  the  wings.  Lymph  follicles  are  numerous 
in  the  intestines. 

The  thin  walls  of  the  lacteals,  of  the  lymph  vessels,  and  of  the 
thoracic  duct  are  made  up  of  two  tunics,  the  inner  being  the  thinner 
and  weaker. 

The  lymphatics  of  the  foot  unite  to  form  the  vessels  along  the  sides 
of  each  toe.  In  palmipedes  there  are  anastomosing  branches  which 
pass  from  the  lateral  vessels  of  one  toe  to  those  of  the  adjoining  toe, 
forming  arches  in  the  uniting  web  of  the  foot.  These  branches  form 
a  small  plexus  at  the  anterior  part  of  the  digito-metatarsal  joint, 
from  which  pass  three  or  four  lymph  vessels.  The  anterior  and 


256  ANATOMY   OF   THE   DOMESTIC   FOWL 

internal  branches  accompany  and  form  a  network  around  the 
blood-vessels.  The  posterior  and  external  branches  receive  the 
lymphatic  vessels  from  the  sole  of  the  foot.  They  then  ascend 
along  the  metatarsus  and  form,  at  its  proximal  articulation,  a  close 
network  from  which  vessels  pass  along  the  tibial  region,  forming  a 
plexus  around  it  as  far  as  the  middle  of  the  leg.  From  this  there 
arises  two  branches.  The  smaller  passes  along  the  anterior  part  of 
the  depression  between  the  tibia  and  the  fibula,  as  far  as  the  knee- 
joint,  where  it  joins  the  other  branch,  which  accompanies  the  blood- 
vessel. The  trunk  formed  by  the  union  of  these  two  vessels  ac- 
companies the  femoral  vessels.  Forming  plexuses  in  its  course,  it 
receives  tributary  vessels  from  the  adjacent  muscles.  The  iliac 
trunk  accompanies  the  femoral  vein  into  the  abdominal  cavity, 
entering  just  in  front  of  the  anterior  end  of  the  pubis.  At  this  point 
it  receives  branches  from  the  lateral  parts  of  the  pelvis  and  then 
separates  into  two  branches.  The  posterior  vessel  receives  some 
lymph  from  the  anterior  lobes  of  the  kidney,  and  from  the  ovary,  or 
testis,  and  communicates  anteriorly  with  a  branch  formed  by  the 
lymph  vessels  adjacent  to  the  anterior  mesenteric  artery,  and 
posteriorly  with  a  large  vesicular  plexus  surrounding  the  aorta  and 
its  branches.  This  plexus  receives  the  lymph  from  the  renal  plexus 
and  from  those  accompanying  the  arteria  media. 

There  are  two  sacral  or  pelvic  vesicles  which  are  situated  at  the 
angle  between  the  tail  and  the  thigh  in  the  posterior  part  of  the 
abdominal  cavity.  Each  vesicle  is  a  trifle  more  than  a  half  inch 
long  and  a  quarter  inch  wide,  and  is  shaped  somewhat  like  a  kidney 
bean.  They  have  muscular  coats  with  striated  fibers.  These  sacs 
are  called  " lymph  hearts." 

The  anterior  division  of  the  femoral  lymphatic  trunk  accompanies 
the  aorta,  on  which  it  forms  a  plexus  with  the  branches  of  the 
opposite  side,  and  with  the  intestinal  lymph  vessels.  These  vessels 
commence  from  a  continuous  plexiform  network  located  between 
the  mucous  and  the  muscular  coat  of  the  intestine.  They  are  larger 
at  this  point  than  where  they  leave  the  intestine  to  pass  through  the 
mesentery.  They  accompany  the  trunk  of  the  anterior  mesenteric 
artery  and  form  a  plexus  around  it. 

Before  reaching  the  region  of  the  aorta,  the  intestinal  lympha- 
tic vessels  communicate  with  the  posterior  division  of  the  femoral 
trunk  and  with  the  lymph  vessels  of  the  ovary  or  of  the  testis. 
After  passing  to  the  region  of  the  aorta  they  receive  vessels  from 


ANGIOLOGY  257 

the  pancreas  and  the  duodenum,  and  terminate  around  the  celiac 
axis  with  the  lymphatics  of  the  liver,  the  proventriculus,  the  giz- 
zard, and  the  spleen,  forming  a  rather  voluminous  plexus  (Lautri). 

The  aortic  plexus  represents  the  receptaculum  chyli  and  gives 
origin  to  two  thoracic  ducts,  mentioned  above,  which  passing  on 
each  side  of  the  bodies  of  the  vertebrae,  pass  one  right  and  one  left, 
over  the  lungs,  from  which  they  receive  lymph  vessels,  and  terminate 
after  receiving  the  lymph  vessels  of  the  wing,  into  the  jugular  vein 
of  their  respective  sides.  The  left  thoracic  duct,  before  emptying 
into  the  vein,  receives  the  trunk  of  the  lymphatics  of  the  left  side  of 
the  neck,  and  the  right  duct  that  of  the  right  side  of  the  neck,  each 
tributary  collecting  lymph  from  all  the  structures  of  its  side. 

The  lymphatics  of  the  wing  follow  the  course  of  the  brachial 
artery,  forming  a  plexus  around  it.  These  vessels  are  well  developed 
in  the  elbow  region.  The  principal  trunk,  following  the  humerus, 
receives  collateral  branches  in  its  upper  third.  This  vessel,  when 
nearing  the  chest,  receives  two  or  three  large  lymph  vessels  from 
the  pectoral  muscles,  and  a  branch  which  accompanies  the  brachial 
plexus. 

The  lymph  vessels  of  the  head  accompany  the  branches  of  the 
jugular  vein,  collecting  the  lymph  from  the  structures  of  the  head 
and  the  neck. 

The  lymphatic  vessels  communicate  at  the  anterior  and  posterior 
oblique  anastomosing  vessels.  At  the  lower  part  of  the  neck  each 
trunk  receives  a  vessel,  which  accompanies  the  carotid  arteries. 
Further  on  they  are  provided  with  a  lymph  gland  which  rests  on  the 
jugular  vein. 

THE  BLOOD  AND  ITS  FUNCTIONS 

The  special  function  of  the  blood  is  to  nourish  all  the  tissues  of  the 
body,  and  in  this  way  to  aid  growth  and  repair.  It  furnishes  mate- 
rial for  the  purpose  of  the  elaboration  of  body  secretions;  it  supplies 
the  organism  with  oxygen;  and  it  carries  away  carbon  dioxid  and 
other  effete  material.  Blood  is  constantly  in  circulation. 

Blood  is  red,  opaque,  and  is,  in  the  fowl,  quite  viscid.  The 
exact  tint  of  the  blood  depends  on  whether  it  is  drawn  from  an  artery 
or  from  a  vein.  Blood  from  a  vein  has  a  purplish  tinge  while  that 
from  an  artery  is  a  bright  scarlet.  The  color  of  blood  is  largely  due 
to  pigment  in  the  erythrocyte,  called  hemoglobin. 

The  reaction  of  the  blood  is  alkaline,  due  to  the  phosphate  and  the 

17 


258  ANATOMY   OF   THE  DOMESTIC  FOWL 

bicarbonate  of  soda.  The  alkalinity  of  the  blood  is  reduced  by  work. 
This  is  due  to  the  formation  of  sarcolactic  acid  in  the  muscle.  The 
odor  of  blood  is  due  to  volatile  fatty  acids.  Each  kind  of  fowl 
has  its  own  peculiar  odor.  The  taste  of  the  blood  is  saltish,  due 
to  a  small  amount  of  sodium  chlorid  it  contains. 

The  blood  consists  of  the  following  substances: 

First,  the  unorganized  part,  or  fluid,  the  liquor  sanguinis  or 
plasma.  It  contains  in  solution  proteids,  extractives,  mineral  mat- 
ter, and  gases.  The  gases  are  held  in  loose  chemical  union. 

The  liquor  sanguinis  constitutes  fully  66  per  cent,  of  the  volume 
of  the  blood.  It  is  albuminous  in  nature  and  contains  a  small 
amount  of  coloring  matter  of  a  fatty  nature.  It  holds  in  solution 
three  proteids — fibrinogen,  serum  globulin,  and  serum  albumin. 

Second,  the  organized  parts,  or  the  cellular  structure  (Fig.  74, 
Nos.  i  to  21).  The  cells  float  in  the  plasma  and  consist  of  three 
groups:  the  erythrocytes,  or  red  blood  cells,  the  leucocytes,  or  white 
blood  cells,  and  the  thrombocytes. 

Erythrocytes. — The  average  number  of  red  cells  (Fig.  74,  No.  21) 
of  the  domestic  fowl  range  between  3,000,000  and  4,000,000  per 
cubic  millimeter.  The  red  blood  cells  are  flattened  and  elliptical 
in  shape,  and  possess  an  oval  elliptical  nucleus.  The  average 
length  is  Ml  00  mcn  and  the  diameter  Ms  00  inch,  or  7  to  8  micra 
in  diameter  and  12  to  13  micra  in  length.  However  the  diameters 
vary  in  different  kinds  of  birds.  The  cytoplasm  is  yellow  and  glassy, 
and  the  nucleus  takes  basic  stains  and  appears  somewhat  picnotic. 

Thrombocytes. — The  thrombocyte  (Fig.  74,  No.  19)  is  of  about  the 
same  length  as  the  erythrocyte  but  somewhat  narrower.  The  nucleus 
is  round,  stains  purple  with  the  Wright's  stain,  and  the  chromatin 
material  is  somewhat  diffused.  The  diameter  of  the  nucleus  is 
nearly  equal  to  that  of  the  cell.  The  cytoplasm  is  pale  and  may 
show  vacuoles  near  the  nucleus.  They  may  contain  small  circum- 
scribed red  structures.  They  vary  somewhat  in  size  and  shape. 
There  are  in  the  domestic  fowl  between  45,000  and  55,000  per  cubic 
millimeter. 

Leucocytes. — There  are,  in  the  blood  of  the  hen,  28,000  to  35,000 
leucocytes  per  cubic  millimeter.  The  leucocytes  may  be  divided 
into  five  distinct  types.  These  are  as  follows: 

Polymorphonuclear  leucocytes  with  eosinophilic  rods  (Fig.  74,  No. 
2)  are  round  and  have  a  diameter  about  equal  to  the  length  of  the 
erythrocyte.  The  nucleus  is  polymorphous;  that  is,  it  has  two  or 


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FIG.  74.— Blood  cells  of  the  fowl.  Wright's  stain.  From  a  S.  C.  Rhode  Island  Red  cock- 
erel, i,  Basophile  (mast  cell)  with  lilac  staining  spherical  granules.  2,  Eosinophile  with 
rod-shaped  acidophile  bodies.  3  and  4,  Eosinophiles  with  acidophile  staining  round  gran- 
ules. 5,  Eosinophile  ruptured.  6,  Mononuclear  leucocyte  with  vacuoles  in  the  cyto- 
plasm. 7  and  9,  Transitional  leucocytes  (first  stage).  8,  Mononuclear  leucocyte.  10, 
n,  and  12.  Small  lymphocytes.  13  and  14,  Large  lymphocytes.  15,  A  lymphocyte.  16, 
Lymphocyte  (nucleus  centrally  located).  17  and  18,  Transitional  leucocyte.  IQ:  Throm- 
bocyte.  20,  Neutrophiie  (poiymorphonuclear)  21.  Erythrocytes. 


ANGIOLOGY  259 

more  lobes.  The  nucleus  stains  a  pale  blue,  and  the  chromatin  is 
diffused.  The  cytoplasm  is  colorless  with  bright  red  staining  spindle- 
shaped  rods.  There  are  28  to  32  per  cent,  of  this  type  of  cell 
the  blood  of  the  hen. 

Polymorphonuclear  leucocytes  with  eosinophilic  granules  (Fig. 
74,  No.  3  and  4)  are  of  about  the  same  shape  and  size  as  the  preced- 
ing. The  nucleus  is  similar  to  the  former  except  that  it  may 
appear  slightly  picnotic.  The  cytoplasm  stains  not  at  all  or  faintly 
blue;  it  contains  round  or  spherical  granules  which  stain  a  dull 
red.  There  is  from  4  to  6  per  cent,  of  this  type  of  eosinophiles  found 
in  the  domestic  fowl. 

Lymphocytes  are  round  in  shape  and  of  about  the  diameter  of  the 
width  of  a  thrombocyte  (Fig.  74,  No.  n).  The  nucleuses  round, 
staining  somewhat  purple,  and  contains  a  diffused  chromatin  material. 
The  cytoplasm  exists  in  only  small  amounts;  it  lies  to  the  side  of  the 
nucleus  and  stains  a  pale  blue.  This  is  the  small  lymphocyte.  A 
similar  cell  but  much  larger  also  exists.  This  is  the  large  lymphocyte 
(Fig.  74,  No.  13).  There  is  from  40  to  44  per  cent,  of  the  lym- 
phocytes in  the  blood  of  the  fowl.  The  small  lymphocytes  are  most 
abundant. 

Large  mononudear  cells  (Fig.  74,  No.  6)  either  round  or  oval, 
in  shape,  whose  diameter  may  be  about  that  of  an  erythrocyte  and 
at  times  much  larger.  The  nucleus  may  be  round,  oval,  or  irregu- 
lar, and  at  times  rather  crescent  or  U-shaped  (Fig.  74,  No.  17).  The 
cytoplasm  is  abundant  and  completely  surrounds  the  nucleus.  The 
cytoplasm  stains  a  paler  blue  than  the  nucleus.  Both  taking  the 
basic  stain  as  do  the  lymphocytes.  These  constitute  18  to  20  per 
cent,  of  the  cells  of  the  blood. 

Mast  cells  or  basophiles  (Fig.  74,  No.  i)  are  of  about  the  same 
size  and  shape  as  the  eosinophiles.  The  nucleus  is  round  or  oval, 
and  stains  a  very  pale  blue.  The  cytoplasm  is  colorless,  mostly  to 
one  side  of  the  nucleus,  and  contains  round  or  spherical  purple  stain- 
ing granules.  This  type  of  cell  constitutes  from  2  to  4  per  cent,  of 
the  white  cells  of  the  blood. 

Structure  of  the  Red  Blood  Cell.— The  red  blood  cell  is  composed 
of  a  spongy  stroma  holding  in  its  meshes  the  red  coloring  matter. 
The  stroma,  or  framework,  of  the  erythrocyte  consists  principally 
of  nucleo-albumin;  it  contains  lecithin,  cholesterin,  and  salts.  The 
red  matter  consists  of  an  albuminous  crystalline  substance  called 
hemoglobin,  which  forms  about  90  per  cent,  of  the  total  solid  matter 


260  ANATOMY   OF   THE   DOMESTIC   FOWL 

of  the  dried  corpuscle.  Each  red  cell  offers  a  certain  absorbing  sur- 
face for  oxygen.  As  the  blood  circulates  through  the  delicate  walls 
of  the  lungs  and  the  air-sacs,  it  takes  up  oxygen;  the  blood  at  the 
same  time  delivers  to  the  air  carbon  dioxid  which  has  been  brought 
from  the  tissues  where  active  cell  metabolism  has  been  going  on. 
This  oxygen  taken  up  by  the  erythrocyte  forms  a  loose  chemical 
union  and  is  known  as  oxy-hemoglobin.  In  this  form  it  is  carried 
to  the  tissues  of  the  body  where  it  is  given  up  by  the  erythrocyte  to 
the  tissues  where  oxidation  is  going  on. 

Hemoglobin  is  a  crystallizable  proteid  substance,  containing  carbon, 
hydrogen,  oxygen,  nitrogen,  sulphur,  and  iron. 

Formation  of  the  Cells  of  the  Blood. — The  red  blood  cells  are 
formed  in  the  red  marrow  of  the  bone. 

Polymorphonuclear  leucocytes  are  formed  in  the  red  marrow  of 
the  bones,  and  the  lymphocytes  in  the  lymph  glands  and  lymph 
follicles. 

The  bird  carries  a  normal  body  temperature  of  105°  to  107°  F. 
The  average  temperature  of  50  mature  hens  and  cocks  was  106.8°  F. 
The  blood  is  of  a  deep  red  color. 

Composition  of  the  Blood. — The  average  composition  of  the  blood 
of  the  domestic  fowl  as  given  by  Owen,  is  as  follows: 

Whole  shed  blood: 

Water 780  parts 

Clot 157  parts 

Albumin  and  salts 63  parts 

1000  parts 
Moist  blood  cells: 

Average  total  weight 456 . 69 

Water 342.52 

Solid  matter 97-5° 

Plasma: 

Total  weight 543-3°  Parts 

Water 495-72  parts 

Solid  matter 30. 72  parts 

Blood  when  drawn  and  allowed  to  stand  soon  coagulates.  In 
the  blood  of  birds  this  process  is  very  rapid,  the  blood  coagulating, 
in  most  instances,  in  about  one-half  minute.  Blood  coagulates  only 
in  the  presence  of  calcium  salts. 

During  life,  the  liquor  sanguinis  is  termed  plasma;  but  after  it 
has  been  shed  from  the  body  and  coagulation  has  taken  place,  the 


ANGIOLOGY  261 

liquid  residue  is  called  serum.     Serum  is  plasma  with  its  modifica- 
tions as  the  result  of  coagulation,  and  as  this  latter  process  is 
brought  about  by  the  production  of  fibrin,  we  may  say  that  senirrris- 
plasma  minus  fibrin-forming  elements. 

The  proteids  of  the  serum  are  serum  globulin,  serum  albumin, 
and  a  ferment  produced  as  the  result  of  coagulation.  As  fibrinogen 
is  used  up  in  the  process  of  coagulation,  it  is  not  found  in  the  serum, 
but  there  is  in  the  serum  a  proteid  known  as  fibrino-globulin.  This 
is  produced  from  fibrinogen  during  the  process  of  fibrin  formation. 
The  following  tabulation  gives  a  clear  idea  of  the  difference  between 
the  proteids  of  plasma  and  of  those  of  serum : 

Proteids  of  Plasma  Proteids  of  Serum 

Fibrinogen  Serum  globulin 

Serum  globulin  Serum  albumin 

Serum  albumin  Fibrin  ferment  (nucleoproteid) 

Fibrino-globulin 

Fibrinogen  is  the  percursor  of  fibrin. 

The  fibrin  of  the  blood  clot  of  the  bird  is  soft  and  very  lacerable. 
The  serum  is  usually  yellow. 

THE  FATE  OF  THE  ERYTHROCYTE  OF  THE  FOWL 

The  power  of  vascular  endothelium  to  ingest  red  blood  corpuscles 
has  been  studied  by  Keys. 

When  bacteria  or  other  minute  foreign  bodies  are  injected  into 
the  blood  stream  of  pigeons,  they  are  rapidly  withdrawn  from  the 
circulation  into  the  tissues  of  the  liver  and  of  the  spleen.  The 
foreign  bodies  are  noted  to  be  contained  within  cells  of  a  distinct 
type,  which  is  found  in  both  liver  and  spleen.  This  type  of  cell 
contains,  in  addition  to  the  foreign  substances  injected,  much  yellow 
pigment,  and  when  tested  for  iron  by  Pearl's  method  gives  a  positive 
Prussian-blue  reaction. 

In  such  specimens  there  is  a  display  of  contrast  to  other  tissues. 
There  is  an  extensive  content  of  cells  possessing  the  distinct  tone  of 
Prussian-blue  iron  reaction.  These  cells  are  distributed  rather 
evenly  throughout  both  the  spleen  and  the  liver,  but  more  numer- 
ously in  the  liver. 

In  the  liver,  under  low-power  magnification,  these  cells  appear  as 
blue  patches,  sharply  differentiated  from  the  red-stained  paren- 
chyma. These  cells  are  larger  in  their  greater  diameter  than  the  liver 


262  ANATOMY   OF   THE   DOMESTIC   FOWL 

cells.  They  vary  much  in  size  and  form.  They  bear  a  constant 
relationship  to  the  venous  capillaries,  and  often  appear  to  occupy 
the  lumen  of  the  vessels.  Under  higher  magnification  it  is  noted, 
however,  that  each  cell  is  an  integral  part  of  the  endothelial  intima 
lining  of  the  capillaries.  They  are  therefore  fixed  tissue  cells,  en- 
gaged by  one  of  its  surfaces  upon  the  reticulum  of  the  vessel  wall, 
with  a  free  surface  bulging  a  greater  or  less  degree  into  the  lumen 
of  the  vessel.  The  attached  surface  of  the  cell  follows  exactly  the 
line  of  the  vessel  wall.  These  cells  are  similar  to  those  described 
for  mammals  by  Kupffer  and  are  called  Kupffer  cells  or  stellate 
cells.  In  the  fowl  Keys  proposes  the  name  hemophages.  The 
nucleus  of  the  hemophage  stains  a  deep  garnet  with  the  carmine  used 
hi  the  above-given  technic,  and  contains  two  or  three  very  dis- 
tinct and  intensely  stained  nucleoli.  In  the  hemophages,  which  are 
more  nearly  flat,  the  nucleus  appears  like  those  of  the  typical  endo- 
thelial cells;  whereas  in  the  protruding  hemophages  of  greater  bulk, 
the  nucleus  is  more  vesicular  and  is  irregularly  pyramidal  in  form. 
Rarely  two  nuclei  are  found  in  one  cell.  Within  this  cell  may  be 
seen  vacuoles  of  the  cytoplasm  which  contain  red  blood  corpuscles. 
These  blood  corpuscles  have  been  phagocyted  from  the  circulating 
blood  stream.  Approximately  one-third  of  the  intimal  cells  are 
hemophages.  Each  hemophage  displays  evidence  that  it  contains, 
or  has  recently  contained,  one  or  more  red  blood  cells.  The  cell  body 
of  the  hemophage  has  no  fixed  morphology,  but  changes  from  time 
to  time  according  to  its  phase  of  phagocytic  activity.  In  a  stage 
which  the  hemophage  has  recently  ingested  a  red  blood  cell,  the 
cell  body  bulges  out  into  the  lumen  of  the  vessel  and  the  nucleus  is 
crowded  to  one  side.  At  this  time  the  red  blood  cell  appears  as 
those  in  the  blood  stream  and  possesses  the  characteristic  staining 
reactions.  The  nucleus  of  the  red  blood  cell  stains  deep  reddish 
brown  and  the  cytoplasm  an  even  yellow  bronze.  In  the  next  stage 
the  cytoplasm  of  the  hemophage  gives  a  diffuse  Prussian-blue  reac- 
tion. Then  in  hemophages  which  represent  later  stages  there  are 
various  stages  of  disintegration  and  digestion  of  the  red  blood  cell. 
The  first  changes  of  the  phagocyted  red  blood  cell  is  hemolysis,  the 
hemoglobin  escaping  into  vacuoles  of  the  cytoplasm  of  the  phago- 
cytic cell,  leaving  the  nucleus-containing  stroma  distinctly  outlined. 
The  stroma  may  retain  the  original  ovoid  form  or  may  become  spher- 
ical; the  nucleus  in  such  instances  remains  ovoid.  Gradually,  both 
the  stroma  and  nucleus  lose  their  staining  reaction  until  finally  the 


ANGIOLOGY  263 

vacuoles  contract  about  a  small  indistinct  remnant  of  the  nucleus, 
which  in  its  turn  ultimately  disappears.  During  this  latter  process 
the  size  of  the  hemophage  gradually  decreases.  The  hemoglobin, 
which  has  escaped  into  the  cytoplasm  of  the  hemophage,  is  seen  to 
undergo  a  series  of  changes.  At  first  the  greater  part  of  the  pigment 
does  not  give  the  iron  reaction  but  retains  its  yellow-bronze  tone 
with  erythrosin  and  occupies  vacuoles  of  various  sizes.  Later  the 
contents  of  the  vacuoles  give  the  iron  react'on  and  with  increasing 
intensity.  Later  there  is  a  gradual  decrease  in  the  staining  reaction 
indicating  that  the  iron  gradually  disappears  from  the  cells  which 
extracted  it  from  the  red  blood  cells  it  digests.  As  a  summary  we 
find,  that  these  cells  take  care  of  the  worn  out  red  blood  cells.  They 
devour  them;  hemolyze  them,  destroying  the  stroma  and  nucleus; 
split  the  hemoglobin  and  free  the  iron;  and  then  finally  return  to 
their  normal  form. 

The  spleen  contains  the  same  type  cells,  but  they  are  fewer  in 
number.  For  the  most  part  they  are  confined  to  the  pulp  cords  and 
have  no  such  evident  relation  to  the  vessel  wall,  or  lumen,  as  in  the 
liver. 

The  function  of  the  cells  of  the  spleen  are  essentially  the  same  ass 
those  in  the  liver.  , 

Iron  freed  from  the  worn  out  red  blood  cells  is  not  retained  by  the 
cells  freeing  it,  nor  is  it  found  in  the  bile.  It  does  not  occur  else- 
where in  the  tissues  of  the  liver  and  spleen.  It  is  possibly  discharged 
into  the  blood  stream,  and  transported  to  the  hemapoietic  tissues. 
Cells  which  hemolyze  red  blood  cells  and  liberate  the  iron  are  to  be 
seriously  throught  of  in  connection  with  bile  formation  since  bili- 
rubin  is  approximately,  if  not  identical  with,  iron-free  hematoidon. 


NEUROLOGY 

The  Nervous  System. — The  nervous  system  is  an  apparatus  by 
means  of  which  animals  appreciate  and  become  influenced  by  im- 
pressions from  the  outer  world.  Animals  react  on  these  impressions, 
and  thus  are  enabled  to  adapt  themselves  to  their  environment. 
This  system  is  the  organic  substratum  of  life,  sensation,  and  motion. 
Broadly  stated,  the  nervous  system  connects  the  various  parts  of 
the  body  with  each  other,  and  to  coordinate  the  parts  into  a  har- 
monious whole  in  order  to  carry  on  the  bodily  functions  methodically 
and  to  control  the  physiological  division  of  labor  throughout  the 
organism. 

The  nervous  system  consists  of  two  parts.  The  first  is  the  cerebro- 
spinal  system,  which  comprises  the  central  nervous  axis,  including 
the  brain  and  the  spinal  cord,  and  the  peripheral  nerves,  including 
the  cranial  and  the  spinal  nerves.  The  second  is  the  sympathetic 
nervous  system.  The  two  parts  of  the  system  are  closely  linked 
together,  and  both  terminate  in  peripheral  nerve  endings,  including 
those  of  special  sense,  of  sensation,  and  of  motion. 

The  cerebrospinal  nerves  especially  preside  over  the  special  senses, 
motion  and  sensation;  and  the  sympathetic  over  the  digestive, 
the  pulmonary,  *and  the  vascular  apparatus. 

From  a  structural  standpoint,  the  nerve  system  consists  of  cell 
elements  peculiarly  differentiated  from  all  other  tissue  cells  in  that 
their  protoplasm  is  extended  in  the  form  of  processes,  often  to  great 
distances  from  the  nuclear  region.  The  cell  elements  are  held  in 
place  by  supporting  tissue  and  receive  an  abundant  blood  supply; 
they  are  partly  of  ectodermal  and  partly  of  mesodermal  origin. 

The  cell  element  of  the  nerve  system,  called  a  neurone,  is  the 
developmental,  structural,  and  functional  unit  of  the  nervous 
system.  It  is  a  single  cell  presenting  unusual  structural  modifica- 
tions. It  comprises  not  only  the  nerve  cell  body  with  its  numerous 
protoplasmic  processes,  or  dendrites,  but  also  the  axone,  which  may 
vary  in  length  from  a  fraction  of  a  millimeter  to  fully  half  the  bird's 
length.  The  bulk  of  the  axone  is  many  times  the  bulk  of  the  cell 
body. 

264 


NEUROLOGY  265 

Certain  non-medullated  axones  are  surrounded  by  a  delicate, 
homogeneous,  nucleated  sheath,  called  the  neurilemma,  or  sheath  of 
Schwann. 

THE  CRANIAL  NERVES 

The  cranial  nerves  have  their  origin  in  the  brain  and  leave  the 
cranial  cavity  in  pairs.  They  are  numbered  numerically  from  before 
backward,  there  being  twelve  pairs  in  all.  The  following  is  a  tabu- 
lation according  to  their  number,  name,  and  function : 

No.       Name  Functional  Nature 

I.  Olfactory  Smell-sense 

II.  Optic  Visual-sense 

III.  Oculomotor  Motor  to  muscles  of  eyeball  and  orbit 

IV.  Pathetic!  Motor  to  superior  oblique  muscle  of  eyeball 

V.  Trifacial  Mixed:  Sensor  to  face  and  tongue.     Motor  to  face 

VI.  Abducentes  Motor  to  External  rectus  of  eyeball 

VII.  Facial  Motor  to  muscles  of  head  and  face 

VIIT.  Auditory  Hearing-sense 

IX.  Glossopharyngeal  Mixed:  Tongue,  pharynx  and  muscles  of  throat 

X.  Vagus  Mixed:  Sensori-motor  to  respiratory  tract  and  part 

of  alimentary  tract 

XI.  Spinal  accessory  Motor  to  muscles  of  pharynx,  neck  and  heart 

XII.  Hypoglossal  Motor  to  muscles  of  the  tongue 

Olfactorius. — Nervus  olfactorius  (Fig.  75,  C,  16).  This  is  the 
nerve  of  smell,  one  of  the  nerves  of  special  sense.  T^ie  organ  of 
smell  consists  of  five  layers  as  follows: 

First,  a  layer  of  olfactory  fibers  extending  in  different  directions 
and  consisting  of  a  dense  plexiform  arrangement  of  the  axones  of 
the  olfactory  cells.  From  this  layer  the  fibers  pass  into  the  layer 
of  olfactory  glomeruli  where  their  terminal  ramifications  mingle 
with  the  dendritic  terminals  of  cells  lying  in  the  more  dorsal  layers, 
to  form  distinctly  outlined  spheroidal  or  oval  nerve  fiber  nests,  the 
olfactory  glomeruli. 

Second,  a  fine  granular  layer  of  basic  substance  containing  round 
cellular  structures,  the  stratum  granulosum. 

Third,  broader  granular,  or  molecular  layer,  having  on  its  inner 
surface  a  row  of  large  pyramidal  cells  which  are  both  small  and  large 
and  which  send  their  dendrites  into  the  olfactory  glomeruli.  Their 
points  are  directed  outward. 

Fourth,  a  layer  of  round  cells  tightly  pressed  together  and  measur- 
ing about  5  microns  in  diameter.  Between  these  cells  are  very 
fine  nerve  fibers. 


266 


ANATOMY    OF    THE   DOMESTIC    FOWL 


B 


FIG.  75. — The  brain  of  a  hen.     Photograph. 

A.  Upper  surface  of  the  brain,     i.   Medulla  oblongata.     2,  Calamus   scrip- 
torius.     3,  Cerebellum.     4,  Optic  lobes.     5,  Transverse  fissure.     6,  Longitudinal 
fissure.     7,   Upper  surface  of  the  left  cerebral  lobe.     8,   Upper  surface  of  the 
right  cerebral  lobe.     9,  Lateral  pillar  of  the  cerebellum. 

B.  The   posterior  surface  of    the  eyeball.      10,  The  sectioned  surface  of  the 
optic  nerve. 

C.  The  inferior  surface  of  the  brain,     n,  Corneo-scleral  juncture.     12,  The 
cornea.     13,  The  solera.     14,  The  optic  nerve.     15,  The  optic  chiasm.     16,  The 
olfactory  lobes.     17,  The  medulla  oblongata.     18,  Tuber  cinererum  et  infundib- 
ulum. 


NEUROLOGY  267 

Fifth,  a  layer  of  epithelial  cells. 

The  peripheral  fibers  and  the  nerve  cell  layers  near  the  hemi- 
spheres disappear  so  that  the  basic  substance  of  the  trabecula 
with  the  hemispheres  form  the  entire  lobe  mass.  On  the  lower 
surface  of  the  hemispheres  there  is  a  long  bundle  of  nerve  fibers 
which  enter  into  the  substance  of  the  olfactory  lobes  and  there 
disappears.  These  fibers  are  medullated.  Non-medullated  fibers 
enter  into  the  makeup  of  the  olfactory  trunk. 

The  original  center  of  the  olfactory  nerve  is  not  in  the  hemisphere, 
but  in  the  same  location  as  the  optic  nerve.  This  nerve  trunk  con- 
sists of  very  fine  non-medulla  ted  fibers.  The  nerves  of  smell  are 
therefore  not  peripheralistic  nerves.  The  nerve  fibers  are  distributed 
to  the  mucous  surface  of  the  turbinated  bones.  Toward  the  front 
they  form  an  expanded  prolongation. 

The  olfactory  nerve,  as  it  emerges  from  the  cone-like  anterior  tip 
of  the  cerebrum,  is  of  considerable  thickness  and  extends  along  with 
the  median  dorsal  artery  of  that  region  above  and  to  the  inside  of 
the  orbit,  under  the  thin  bony  structure.  Before  its  termination 
into  the  posterior  turbinated  bones,  it  is  crossed  by  the  superior 
maxillary  division  of  the  fifth  pair  of  cranial  nerves.  It  extends  as 
far  as  the  pituitary  membrane  of  the  turbinate  bones  upon  which  its 
filaments  are  distributed  radially. 

The  Opticus. — The  nervus  opticus  (Fig.  75,  No.  C,  14)  the  second 
cranial,  is  the  nerve  of  sight.  The  optic  lobe,  or  tuberculum 
bigeminum  lies  at  the  base  of  the  brain  on  each  side  of  the  optic 
tract. 

From  the  optic  lobes  the  two  trunks  pass  forward  along  the  under 
surface  of  the  cerebri,  forming  the  optic  chiasm  at  the  hypophysis 
(Fig.  75;  No.  C,  15),  at  which  point  the  nerve  fibers  originating  from 
the  right  side  pass  to  the  left,  and  vice  versa.  From  the  chiasm  the 
true  optic  nerves  pass  forward  to  the  posterior  surface  of  the  eyeball. 
They  are  composed  of  a  bundle  of  very  fine,  marrow-like  nerves. 
These  fibers  enter  into  the  ganglionic  cells  of  the  retina.  By  re- 
moval of  the  finely  adherent  neurilemma,  the  optic  nerve  is  seen  to 
be  composed  of  parallel,  longitudinal  lamellae,  the  margins  of  which 
are  mostly  free  on  one  side. 

The  Motor  Oculi.— The  motor  oculi  (Fig.  62,  No.  C,  10),  the 
third  crania]  nerve  is  a  motor  nerve.  It  originates  close  to  the 
base  of  the  brain  behind  the  position  of  the  hippocampus  of  mam- 
mals on  the  inner  side  of  the  crus  cerebri,  and  also  on  the  inner 


268  ANATOMY    OF   THE   DOMESTIC   FOWL 

somatic  column  close  below  and  somewhat  aside  from  the  aqueduct 
of  Sylvius.  The  nerve  leaves  the  brain  cavity  through  a  distinct 
foramen  near  the  foramen  opticum,  and  supplies  the  following  eye 
muscles:  first,  after  entering  the  orbit,  it  sends  a  branch  upward 
to  the  inferior  portion  of  the  inferior  rectus;  then,  it  gives  off  the 
thick  ramus  ciliaris.  The  trunk  then  extends  under  the  optic 
nerve  and  passes  forward  to  innervate  the  inferior  rectus,  the 
internal  rectus,  and  the  inferior  oblique.  A  ciliary  ganglion  forms 
on  the  trunk. 

The  Patheticus. — (Fig.  62,  No  C,  n)  is  a  small  motor  nerve, 
originating  close  to  the  sulcus  centralis,  in  the  circle  of  the  center 
brain  over  the  valve  of  Vieussens,  between  the  posteriors  of  the 
optic  lobes.  It  extends  in  a  dorsal  direction  between  the  cere- 
bellum and  the  lobus  opticus,  to  the  posterior  of  the  latter  of 
which  it  then  forms  a  loop  ventrally.  Lying  close  to  the  optic 
foramen  it  passes  through  a  fine  opening  into  the  eye  cavity  and 
supplies  the  superior  oblique  muscle  of  the  eye.  During  its  course 
it  passes  dorsally  over  the  optic  nerve,  and  then  crosses  dorsally 
over  the  ophthalmic  division  of  the  fifth  pair  of  cranial  nerves  and 
the  internal  rectus  muscle. 

The  Trifacialis. — (Fig.  62,  No  C,  12).  This,  the  fifth  cranial, 
is  a  mixed  nerve  and  is  divided  into  two  parts,  portio  major  and 
portio  minor. 

The  portio  major  originates  in  the  ganglion  cells  of  the  posterior 
part  of  the  brain.  Commencing  near  the  medulla  oblongata  it 
passes  through  the  posterior  part  of  the  brain,  then  upward  and 
outward;  and  along  its  route  it  forms  the  Gasserian  ganglion,  which 
lies  partly  in  the  cranial  cavity  or  in  its  wall. 

The  portio  minor  consists  of  the  downward  passing  fibers  contain- 
ing the  motoric  elements  which  are  distributed  to  the  muscles  of  the 
jaw  and  of  the  eye.  The  roots  are  found  in  the  ganglion  from  the 
center  and  back  brain,  close  below  the  pathetic  nerve  origin,  where 
the  pathetic  passes  between  the  lobus  opticus  and  the  pars  pedun- 
cularis;  it  then  takes  a  lateral  course  between  the  two. 

The  fibers  of  the  portio  minor  do  not  take  part  in  the  formation 
of  the  Gasserian  ganglion,  but  are  only  partly  surrounded  by  it. 

There  are  three  nerve  trunks  given  off  of  the  trifacialis:  the  oph- 
thalmic, the  superior  maxillary,  and  the  inferior  maxillary. 

The  ophthalmic  division  of  the  fifth  nerve  is  the  smallest  of  the 
three  branches.  It  emerges  directly  from  the  Gasserian  ganglion, 


NEUROLOGY  269 

and  passes  through  a  narrow  bony  canal  in  the  base  of  the  brain, 
below  the  pathetic  and  the  abducens,  and  through  the  foramen 
ophthalmicum.  It  then  enters  the  eye  cavity  above  the  optic  nerve,  - 
and  on  the  wall  of  the  cavity  extends  downward,  and  with  regard 
to  the  eyeball,  dorsally  lying  close  to  the  rectus  internus  muscle 
and  close  to  the  surface  of  the  eyeball.  It  passes  along  the  olfac- 
tory nerve,  extends  under  the  superior  olbique  muscle,  and  finally 
reaches  the  inner  angle,  or  canthus,  of  the  eye.  It  here  divides  into 
the  recurrent  externa  and  the  ethmoidalis.  The  ethmoidalis  branch 
is  a  straight  continuation  of  the  ophthalmic.  It  extends  along  close 
to  its  fellow  of  the  opposite  side,  and,  over  the  vomer,  splits  into  two 
branches.  The  smaller  of  these  branches  breaks  through  the  bone 
cells  of  the  jaw,  continues  upon  its  ventral  surface  in  a  furrow  ex- 
tending forward,  and  terminates  in  the  gum  region.  It  supplies  the 
gum  and  point  of  the  beak.  The  larger  branch  enters  into  the  cell 
substance  extending  to  the  tip  of  the  beak,  in  its  course  sending 
out  a  number  of  fine  filaments,  which  spread  out  along  the  outer 
surface.  At  this  point  these  two  branches  may  fuse.  The  larger 
branch  is  endowed  with  the  sense  of  touch. 

The  recurrent  externa  divides  shortly  after  leaving  the  main  trunk 
of  the  eye  cavity  passes  over  the  lacrimal  gland.  It  gives  two 
branches  to  this  gland  and  one  to  the  membrana  nictitans,  and 
innervates  the  upper  eyelid.  It  then  emerges  from  the  eye  cavity, 
passing  over  the  os  lacrimale,  and  gives  one  or  more  branches  to 
the  integument  of  this  region,  including  the  comb.  This  branch 
is  large  in  birds  with  a  large  comb.  Branches  pass  in  front  of  the 
lacrimal  bone  through  the  outer  nasal  cavity  and  into  its  deeper 
structure. 

Shortly  after  the  ophthalmic  branch  has  entered  into  the  eye 
cavity  and  before  it  crosses  the  optic  nerve,  it  gives  a  fine  branch 
to  the  motor  occuli. 

The  second  and  the  third  branches  of  the  fifth  cranial  nerve  are 
mixed.  They  contain  elements  of  both  the  portio  major  and  the 
portio  minor.  These  two  branches  come  from  the  lower  part  of  the 
outer  region  of  the  ganglion,  and  pass  together  through  a  cavity 
which  is  located  between  the  os  petrosum  and  alae  and  basis  sphe- 
noid, and  then  branch. 

The  ramus  secundus,  or  superior  maxillary  division,  of  the  tri- 
facial,  is  the  second  branch  and  passes  into  the  orbit  below  the 
optic  nerve  and  the  eyeball.  It  is  called  the  recurrent  infra -orbitale. 


270  ANATOMY   OF  THE   DOMESTIC  FOWL 

It  gives  an  ascending  branch  to  the  gland  of  Harder,  one  to  the 
conjunctiva,  one  to  the  membrana  nictitans,  and  one  to  the  eyelids. 
It  also  gives  a  branch  to  the  skin  below  the  eye  and  to  the  angle 
of  the  mouth.  This  latter  branch  is  called  the  recurrent  subcutaneous. 
These  two  branches  communicate  with  the  recurrent  nasal  ciliaris 
of  the  first  trigeminus  branch.  The  second  branch  passes  below  the 
nasal  opening,  then  passes  on  and  forms  the  alveolar  nerve  on  the  side 
between  the  gums.  It  sends  several  recurrent  posterior  branches 
to  the  elevations  on  the  back  part  of  the  mouth.  It  extends  for- 
ward to  the  point  of  the  beak. 

The  inferior  maxillary  division  of  the  fifth  is  larger  than  the 
other  two.  It  is  directed  downward  and  outward  then  upward  to 
the  temporal  region.  At  the  temporal  region  it  divides  into  five 
parts.  It  gives  a  branch  to  the  temporalis  muscle,  one  to  the 
pterygoid  muscle,  and  one  to  the  mylo-hyoideus.  The  main  branch 
gives  twigs  to  the  parotid  gland  region  and  enters  into  the  dental 
canal  of  the  lower  jaw.  Numerous  filaments  break  through  the 
lower  jaw  bone,  and  then  spread  out  on  the  skin  and  rim  of  that  bone. 
The  largest  branch,  called  the  recurrent  maxillaris  externa,  comes 
out  near  the  coronoid  process.  The  rest  of  the  trunk  extends  to, 
and  comes  out  of,  several  foramina  at  the  anterior  point  of  the  jaw 
bone. 

These  filaments  are  contained  in  grooves  or  cavities  of  the 
lower  jaw  and  terminate  in  touch  buds. 

The  trifacialis  fuses  with  the  other  cranial  nerves  and  with  the 
sympathetic  nervous  system.  Some  of  these  fusions  are  as  follows: 
The  recurrent  ophthalmica  fuses  with  the  orbito-nasalis  ganglion. 
Indirect  fusion  of  the  recurrent  maxillary  division  of  this  nerve 
takes  place  near  the  Gasserian  ganglion  through  the  sympathetic 
nerves,  the  temporo-lacrimalis,  the  facial  nerves,  the  large  cervical 
ganglion,  and  indirectly  with  the  glosso-pharyngeal  and  the  vagus. 
This  fusion  has  been  called  the  superior  recurrent  branch  of  the 
trigeminus,  or  trifacialis. 

There  is  a  direct  fusion  of  the  superior  recurrent  maxillary  di- 
vision of  the  fifth  just  before  entering  the  upper  jaw.  This  fusion 
is  with  the  spheno-palatine  ganglion  and  the  sympathetic  carotidis 
cephalica,  and  also  with  the  large  cervical  ganglion. 

The  Abducens  (Fig.  62,  No.  C,  13). — This  nerve  originates  in  the 
somatic  and  motoric  column  along  with  the  other  nerves  of  the  eye 
muscles.  Its  nucleus  lies  in  the  circle  of  the  pars  commissuralis  of 


NEUROLOGY  271 

the  cerebellum.  The  nerve  then  passes  ventrally,  as  does  the  mo- 
toris  oculi  and  leaves  the  brain  along  the  median  line.  This  is  a 
comparatively  large  nerve  and  passes  somewhat  laterally  and 
ventrally  from  the  foramen  opticum  through  a  canal  in  the  sphenoid. 
It  then  enters  the  orbital  cavity.  Some  muscular  twigs  are  given 
off  to  the  quadra tus  and  to  the  pyramidalis  muscle.  This  nerve 
also  innervates  the  external  rectus  muscle  of  the  eye.  The  ab- 
ducens  anastomoses  with  the  ramus  ciliaris  and  the  ophthalmic  nerve 
and  gives  fine  nerve  twigs  to  the  ramus  ciliaris  externus  of  the  cil- 
iary ganglion. 

The  Facialis  and  the  Acusticus. — The  facial  nerve  originates  with 
the  auditory  (Fig.  62,  No.  C,  14  and  15)  in  a  very  vaguely  known 
manner,  from  the  cerebellum.  It  divides  into  three  parts. 

The  first  of  these  probably  comes  from  the  complex  ganglion  with 
the  posterior  roots  of  the  auditory.  This  part  belongs  to  the  somatic 
sensory  group  of  nerves.  From  this  same  group  originates  the  audi- 
tory, which  spreads  out  into  the  cochlea  and  takes  the  impressions 
of  sound.  This  nerve  is  short  and  thick,  and,  at  the  point  where  it 
loses  its  medullary  covering  on  entering  the  cochlea,  there  is  devel- 
oped a  ganglion.  This  ganglion  is  similar  to  the  spinal  ganglia. 

The  second  part  is  provided  with  one  root  which  originates  mesi- 
ally  and  ventrally,  from  the  deeper  ganglion  cells.  Some  of  the 
fibers  from  this  root  constitute  the  vestibular  branches.  They 
accompany  the  auditory  and  supply  the  anterior  part  of  the  ear 
labyrinth  and  the  semicircular  canals.  The  larger  part  of  the 
fibers  of  this  trunk  make  up  the  intermediate  part  of  the  facial. 
The  geniculate  ganglion  is  formed  at  their  fusion.  The  sympathetic 
spheno-palatine  nerve  emerges  from  this  ganglion,  coming  out  of  the 
aqueduct  of  Fallopius. 

The  third  part,  called  the  portio  dura,  is  the  main  facialis.  It  is 
located  opposite  the  auditoria  intermedia.  Its  roots  may  be  traced 
to  the  complex  ganglion,  from  which  they  take  a  direction  ventrally 
from  the  median  portion. 

The  facialis,  after  emerging  from  the  aqueduct  of  Fallopius, 
takes  a  curved  course  and  partly  fuses  with  the  sympathetic  temporo- 
lacrimalis  on  the  upper  posterior  wall  of  the  ear  drum.  It  is  here 
accompanied  by  the  carotid  and  the  cephalic  arteries.  It  leaves 
the  ear  drum  through  an  opening  in  the  quadrate  bone,  giving  off  a 
large  branch  to  the  digastricus  muscle  and  a  small  one  to  the  sta- 
pedius  of  the  columella  auris.  The  facialis  trunk  is  quite  large.  It 


272  ANATOMY   OF   THE   DOMESTIC   FOWL 

then  passes  downward  along  the  quadrate  bone,  where  it  receives  a 
large  branch  from  the  glosso-pharyngeus.  This  nerve  also  gives 
branches  to  the  mylo-hyoideus  and  the  stylo-hyoideus  muscle,  crosses 
laterally  the  glosso-pharyngeus,  and  finally  fuses  with  branches 
of  the  subcutaneous  and  with  the  first,  the  second,  the  third,  and 
the  fourth  cervical  nerves.  After  this  fusion  the  nerves  innervate 
the  skin  of  the  anterior  of  the  neck  and  the  constrictor  colli  muscle. 

The  facialis  anastomoses  as  follows:  with  a  fine  branch  of  the 
sympathetic  temporo-lacrimalis,  indirectly  with  the  ramus  trigemi- 
nus,  with  the  large  cervical  nerve  ganglion  and  with  the  spheno- 
palatine  ganglion  and  nerve. 

The  Vagus  Group. — The  ninth,  the  tenth,  and  the  eleventh  cra- 
nial nerves  are  by  some  anatomists  called  the  vagus  group,  first  so 
called  by  Willis.  They  are  made  up  of  both  sensory  and  motor 
nerves. 

The  Glosso-pharyngeus. — The  roots  of  the  glosso-pharyngeus  (Fig. 
62,  No.  C,  16;  Fig.  76,  No.  13)  emerge,  along  with  those  of  the  vagus, 
from  the  medulla  oblongata,  and  enter,  as  a  short  trunk,  the  foramen 
jugulare  et  caroticum.  Between  these  two  nerves  there  is  usually 
found  a  thin  portion  of  bone.  The  trunk  of  the  glosso-pharyngeus 
forms  a  ganglion  in  the  foramen  jugulare  et  caroticum  where  it 
receives  connecting  branches  from  the  near-by  ganglion  radicis  and 
vagus  nerve.  The  glosso-pharyngeus  passes  out  of  the  foramen 
jugulare  et  caroticum  above  the  large  superior  smpathetic  nerve  gan- 
glion, with  which  it  communicates.  The  glosso-pharyngeus  passes 
diagonally  over  the  ramus  temporo-lacrimalis  of  the  sympathetic 
system,  and  then  receives  a  very  strong  branch  from  the  vagus  (Fig. 
76,  No.  12).  It  sends  a  short  branch  to  the  recurrent  lacrimalis  of 
the  sympathetic  system.  At  this  point  there  is  formed  a  reddish- 
yellow  ganglion,  the  petrosal  ganglion,  which  is  similar  to  the  petrosal 
ganglion  of  mammals.  Frequently  it  is  found  close  below  the  large 
superior  cervical  nerve  ganglion.  The  petrosal  ganglion  is  fre- 
quently connected  by  special  fibers  with  the  cervical  nerve  ganglion, 
the  large  superior  cervical  nerve  ganglion  and  the  ganglion  radicis 
vagi.  The  glosso-pharyngeus  is  divided  into  the  following  branches. 

First,  the  recurrent  pharyngeus  which  gives  branches  to  the  upper 
part  of  the  throat  and  which  is  tortuous  in  its  course.  It  receives 
a  branch  from  the  superior  cervical  nerve  ganglion  and  gives  off 
branches  to  the  salivary  glands  and  papillae  of  the  posterior  tongue 
region. 


NEUROLOGY 


273 


Second,  the  recurrent  lingualis,  which  passes  with  the  lingual 
artery  over  the  hyoid  bone  to  the  base  of  the  tongue  and  to  the 
papillae.  Another  branch  passes  below  the  tongue  bone  and  sup- 


plies  the  tongue  and  the  pharynx.     The  glosso-pharyngeal  is  a  mixed 
nerve. 

The  Vagus. — The  vagus,  or  pneumogastricus  (Fig.   18,  No.  5; 
Fig.  62,  No.  C,  17;  Fig.  76,  No.  12),  a  mixed  nerve,  forms  a  ganglion 


18 


274  ANATOMY  OF   THE  DOMESTIC  FOWL 

in  the  foramen  through  which  it  passes.  The  foramen  lies  between 
the  os  petrosum  and  os  occipitale,  close  to  the  foramen  jugulare, 
above  and  to  the  inside  of  it. 

The  ganglionic  root  of  the  vagus  communicates  with  the  superior 
cervical  nerve  ganglion.  The  vagus,  after  coming  out  of  the  foramen, 
takes  up  branches  of  the  spinal  accessory,  passes  to  the  superior 
nerve  ganglion,  crosses  the  carotid  artery,  and  then,  accompanied 
by  the  internal  jugular,  it  connects  by  a  branch  with  the  hypoglossal. 
It  then  communicates  with  the  petrosal  ganglion,  and  receives  a 
long  branch  from  the  superior  cervical  ganglion.  It  then  extends 
along  the  neck  with  the  jugular  vein  and  often  fuses  with  the  sym- 
pathetic ganglionic  plexuses.  As  it  passes,  it  is  interwoven  with  the 
glosso-pharyngeus,  but  each  nerve  element  retains  its  own  individu- 
ality. Extending  down  the  neck,  on  entering  the  thoracic  cavity, 
it  lies  between  the  plexus  brachialis  and  the  carotid  artery.  Then 
it  passes  below  the  subclavian  artery,  and  between  the  bronchial 
tubes,  the  aorta  pulmonalis,  and  the  subclavian  vein.  Then  ven- 
trally  it  rests  upon  the  glands,  and  the  right  and  the  left  vagi  fuse 
or  unite.  From  here  they  radiate  down  to  the  stomach  in  fan  shape, 
and,  continuing,  they  fuse  with  the  sympathetic  system. 

The  other  branches  of  the  vagus  are: 

The  first  branch  is  the  recurrent  laryngeus,  which  supplies  the 
lower  end  of  the  bronchial  tubes,  and  the  esophagus,  then  enters 
above  the  bronchus  near  the  origin  of  the  subclavian  artery  as  the 
recurrent  cardiacus. 

The  second  are  the  recurrent  pulmonale  which  pass  into  the  lungs, 
each  fusing  with  its  fellow  from  the  opposite  side,  and  giving  off 
branches  inferior  to  the  vena  cava  including  a  branch  to  the  heart. 

The  third  are  the  recurrent  hepatici  which  pass  through  the  dia- 
phragm and  are  distributed  to  the  liver. 

The  Accessorius  Spinalis. — This  is  a  very  small  motor  nerve 
(Fig.  62,  No.  C,  18).  It  comes  out  between  the  dorsal  and  the  ventral 
root  of  the  third  cervical  nerve.  It  lies  close  to  the  neck  and  extends 
anteriorly,  receiving  roots  from  the  first  and  the  second  cervical 
nerve.  It  passes  through  the  occipital  foramen  into  the  brain  cavity 
and  then  enters  the  ganglion  radicis  vagi.  It  passes  out  of  the  cranial 
cavity  through  the  foramen  jugulare.  It  then  partly  fuses  with  the 
vagus  and  partly,  as  a  fine  branch,  with  the  subcutaneous  colli. 

The  Hypoglossus. — The]  hypoglossus  is  a  motor  nerve  (Fig.  62, 
No.  C,  19).  It  originates  anterior  to  the  eleventh  pair  of  cranial 


NEUROLOGY  275 

nerves,  and  from  the  same  ganglion  as  the  abducens  and  the  motor 
oculi.  It  leaves  the  medulla  oblongata  from  its  ventral  surface,  and 
passes  with  a  posterior  and  an  anterior  branch  out  of  the  cranial 
cavity  through  two  separate  foramina  in  the  os  occipitale  laterale. 
The  posterior  branch,  much  smaller  than  the  anterior,  passes  between 
the  cranial  bones  and  the  cervical  sympathetic  nerve;  it  then  passes 
at  right  angles  through  the  rectus  capitis  anticus,  and,  while  closely 
following  the  carotid  artery,  it  fuses  with  the  anterior  branch. 
The  larger,  anterior  branch,  much  stronger  than  the  posterior,  sends 
a  short  strong  branch  to  the  complexus  muscle.  The  rest  of  this 
branch,  which  probably  has  sympathetic  elements,  is  disposed  as  is 
a  spinal  nerve.  It  crosses  the  sympathetic  nerve,  and  at  this  point 
forms  a  typical  cervical  sympathetic  ganglion.  It  also  forms  a 
short  loop  with  the  recurrent  ventralis  of  the  first  cervical  plexus. 
From  this  loop,  after  it  has  given  off  several  branches  to  the 
muscles  of  the  neck,  it  gives  off  one  or  two  strong  branches,  which 
fuse  with  each  other  and  with  the  posterior  thin  branch,  thus  form- 
ing the  trunk  of  the  hypoglossus.  It  receives  many  elements  from 
the  first  cervical  nerves. 

The  hypoglossus  sometimes  communicates  with  the  vagus,  crosses 
over  the  latter,  and  divides  itself  into  two  main  branches,  as  follows: 

First,  the  recurrent  laryngo-lingualis,  which  passes  between  the 
cornua  of  the  os  hyoideum  and  the  larynx  to  the  anterior  part, 
and  furnishes  the  principal  tongue  muscles.  It  extends  along  the 
inferior  surface  of  the  tongue  and  fuses  with  the  one  of  the  other 
side  and  extends  to  the  free  tip  of  the  tongue.  This  nerve  probably 
receives  sensory  elements  from  the  second  root  and  from  the  con- 
fluent of  the  first  cervical  nerve.  This  form  of  anastomosis  is  well 
marked  in  birds  with  thick  tongues,  as  ducks. 

Second,  the  recurrent  laryngeus  furnishes  the  muscles  of  the  su- 
perior larynx  and  of  the  tongue  skeleton.  It  extends  downward 
and  also  furnishes  the  muscles  of  the  trachea.  It  follows  the  course 
of  the  jugular  vein  and  at  the  entrance  of  the  chest  supplies  the  fur- 
cula.  The  nerve  passes  into  the  thorax,  downward  along  the  side  of 
the  bronchial  tubes,  and  supplies  innervation  to  all  the  muscles  of 
the  inferior  larynx. 

THE  SPINAL  CORD 

Structure  of  the  Cord. — The  spinal  cord  is  called  the  myelon  or 
medulla  spinalis.  It  is  a  comparatively  large,  white,  irregularly 


276  ANATOMY   OF   THE  DOMESTIC   FOWL 

cylindrical  cord,  flattened  from  above  downward.  It  extends  from 
the  foramen  magnum  at  the  base  of  the  medulla  to  the  caudal  portion 
of  the  spinal  canal  where  it  terminates  in  a  fine  filament.  In  order 
to  allow  considerable  motion  of  the  spinal  column  without  danger  of 
injury  to  the  spinal  cord,  the  cord  is  loosely  suspended  in  the  canal. 
The  meninges,  or  coverings,  are  continued  from  the  brain.  In  addi- 
tion to  these  there  are  to  be  found  arteries,  veins,  and  nerves  en- 
tering and  others  making  their  exit  .from  the  canal  and  from  the 
cord.  At  the  cervico-dorsal  juncture,  where  the  brachial  plexus 
is  given  off,  the  cord  is  enlarged.  There  is  another  enlargement  at 
the  point  where  the  lumbo-sacral  plexus  is  given  off.  At  this  point, 
superiorly,  there  is  a  longitudinal  cavity  called  the  sinus  rhomboi- 
dalis.  This  sinus  contains  a  gelatinous  substance.  There  is  a  pair 
of  nerves  given  off  at  each  intervertebral  foramen.  Thus  there  are 
as  many  pairs  of  spinal  nerves  as  there  are  vertebral  segments.  The 
inferior  root  is  the  motor  root  and  carries  the  impulses  from  the 
cord  to  the  periphery.  The  superior  root  is  the  sensory  branch 
and  carries  the  impulses  from  the  periphery  to  the  cord,  and  thence 
the  impulse  is  carried  to  the  centers  in  the  brain.  The  sensory 
and  the  motor  roots  are  of  about  equal  size.  The  inferior  have  more 
numerous  filaments.  The  ganglion  on  the  superior  or  sensory  root 
is  relatively  large.  In  the  sacral  region  the  sensory  and  the  motor 
branches  pass  through  their  own  bony  canal. 

White  rami  communicantes  are  given  off  at  each  intervertebral 
foramen  to  the  sympathetic  system  and  gray  rami  are  received  from 
the  sympathetic  ganglia.  Thus  there  is  established  a  direct  commu- 
nication between  the  sympathetic  and  the  spinal  system.  There  is  a 
ganglion  on  the  superior  root  just  outside  the  spinal  cord. 

The  ganglionic  portion,  or  gray  matter,  is  arranged  in  the  center 
of  the  cord  in  two  comma-shaped  parts  forming  an  X.  The  white 
matter,  or  the  material  forming  the  fibers,  is  arranged  around  the 
central  ganglionic  portion. 

The  spinal  cord  may  be  divided  into  two  lateral  symmetrical 
halves.  There  are  two  longitudinal  fissures,  one  on  the  upper  and 
the  other  on  the  lower  half.  The  upper  called  the  superior  median, 
fissure  is  narrow  but  deep.  The  one  on  the  inferior  side,  called  the 
inferior  median,  is  usually  more  pronounced.  The  superior  parts 
of  the  gray  matter  are  called  the  superior  cornua,  or  horns;  the 
inferior  parts  the  inferior  cornua,  or  horns.  The  center  of  the  cord 


NEUROLOGY  277 

is  pierced  by  a  central  canal  which  communicates  with  the  fourth 
ventricle  at  the  calamus  scriptorius. 

STRUCTURE  OF  THE  NERVE  TRUNKS  AND  GANGLIA 

The  protoplasmic  processes  called  dendrites  have  a  similar  struc- 
ture to  the  cell  body.  The  dendrites  branch  dichotomously,  become 
rapidly  smaller,  and  usually  end  at  no  great  distance  from  the  cell 
body. 

The  axone  or  axis  cylinder  process,  differs  from  the  cell  body  and 
from  the  dendrites.  It  does  not  contain  chromophilic  granules. 
It  consists  entirely  of  neurofibrils  and  perifibrillar  substance.  It 
emerges  from  the  cell  at  an  enlargement  known  as  the  axone  hill. 
This  hill  is  free  from  chromophilic  bodies. 

Nerves  are  divided  into  two  kinds,  medullated  and  non-medullated. 

Medullated  nerves  are  divided  into  two  kinds:  medullated  nerves 
with  a  neurolemma,  and  medullated  nerves  without  a  neurolemma. 

Medullated  nerves  with  a  neurolemma  consists  of  an  axone,  a 
medullary  sheath,  and  a  neurolemma.  A  delicate  membrane  called 
an  axolemma,  or  periaxial  sheath  envelops  the  axone.  The  medullary 
sheath  called  myelin,  is  semifluid,  somewhat  resembling  fat.  The 
outer  covering  is  the  neurolemma,  or  sheath  of  Schwann.  It  is  a 
delicate,  structureless  membrane  which  incloses  the  myelin.  There 
is  under  this  sheath  an  occasional  oval  nucleus.  At  intervals  there 
are  constrictions,  or  nodes,  called  the  constrictions  of  Ranvier.  The 
part  between  the  nodes  is  called  the  internode. 

The  medullated  axones  without  a  neurolemma  are  the  medullated 
nerve  fibers  of  the  central  nervous  system. 

The  non-medullated  axones,  or  non-medullated  nerve  fibers,  are 
divided  into  non-medullated  axones  with  and  those  without,  a  neuro- 
lemma. 

The  non-medullated  axone  without  a  neurolemma  is  merely  a  naked 
axone.  They  are  confined  to  the  gray  matter  and  to  the  beginnings 
and  endings  of  sheath  axones,  all  the  latter  being  uncovered  for  a 
short  distance  after  leaving  the  nerve  cell  body  and  also  just  before 
reaching  their  terminations. 

The  long  axones  serve  to  make  connections  with  the  peripheral, 
or  distant,  nerve  cell,  muscle  cell,  or  gland  cell;  while  the  shorter 
axones  of  certain  neurones  divide  into  terminal  branches  in  the 
immediate  vicinity  of  its  cell  body,  presumably  to  come  into  relation 
with  other  nerve  cells  in  the  same  or  adjacent  groups. 


278 


ANATOMY   OF   THE   DOMESTIC   FOWL 


FIG.  77. — Histological  structure  of  tissues. 

1.  Non-striated  or  involuntary  muscle  cell.     a.  i,   Nucleus;    2,  Protoplasm. 
b.    Transverse  section  showing   nuclei  in    the  center  of   the  cells  that  are  cut 
through  the  nuclear  zone.      c.  A  cross-section  of  the  connective  tissue  which 
binds  together  the  muscle  cells,     d.  A  section  showing  the  so-called  intercellular 
bridges. 

2.  A  cross-section  of  the  rectus  abdominalis.     i,  The  endomysium  which  binds 
the  cells  into  primary  fasciculi  or  bundles.     2,  The  perimysium  which  surround 
the  bundles  of  fasciculi.     3,  The  epimysium  which  surrounds  the  muscle.     These 
binding  structures  are  white  fibrous  connective  tissue. 

3.  A  longitudinal  section  at  the  juncture  of  a  muscle  and  tendon,     a,  The 


NEUROLOGY  279 

Neurones  are  devoted  to  the  maintenance  of  functions.  Repro- 
ductive neurones  are  so  arranged  as  to  receive  afferent  nerve  impulses 
from  other  tissues;  emissive  neurones  give  off  efferent  nerve  impulses. 
The  former  are  sensory  neurones;  the  latter  are  motor  neurones 
if  connected  with  muscles,  and  excito-glandular  if  connected  with 
gland  cells.  The  basis,  then,  of  the  nerve  system  is  a  series  of  neu- 
rones, with  projecting  and  association  processes,  coordinated  for 
the  purpose  of  performing  specific  actions  manifested  either  by 
motion,  by  trophic  changes,  or  by  the  apperception  of  stimuli  of 
a  chemic,  mechanic  (tactile  and  auditory),  thermal,  or  photic  nature. 

The  whole  of  the  nerve  structure  is  composed  of  the  nerve  tissue 
and  supporting  connective  tissue.  The  neurones  constitute  the 
nerve  tissue,  while  the  supportive  tissue  is  composed  of  neuroglia 
and  of  white  fibrous  tissue  derived  either  from  the  investing  mem- 
brane or  from  the  sheaths  of  its  numerous  vascular  channels. 

The  neurones,  or  nerve  cells,  exhibit  marked  variations  as  to  ex- 
ternal characters,  dimensions,  and  form.  The  neurone  presents  a 
swollen  cell  mass  and  a  nucleus;  it  is  known  as  the  ganglion  cell. 
From  this  cell  body  are  given  off  a  number  of  processes  of  two  dis- 
tinct kinds:  first,  protoplasmic  processes,  which  are  commonly 
branched,  called  dendrites;  second,  a  single,  thinner,  and  paler  proc- 
ess; the  axis  cylinder  process. 

juncture  between  the  muscle  and  tendon.  Note  the  many  nuclei  in  both  muscle 
and  tendon.  This  is  voluntary  or  striated  muscle  which  make  up  the  dermal, 
dermo-osseous  and  skeletal  muscles. 

4.  A  longitudinal   section  of    heart   muscle,     a,    Connective-tissue   cell,      b, 
Nucleus  of  a  muscle  cell,     c,  Cement  line  between  the  muscle  discs,     d,  The 
cell  or  segment. 

5.  A  bipolar  ganglionic  nerve  cell,     a,  The  nucleus.     &,  The  nucleolus.    c,  The 
fibrillar  structure,     d,  The  medullary  sheath. 

6.  A  diagram  showing  the  scheme  of  the  peripheral  nerve  trunk,     a.   The 
neuraxis  of    the   peripheral  sensory  neurone,     b,   The  spinal  ganglion  of  the 
superior  or  sensory  root,     c,  The  dendrite  or  peripheral  nerve  fiber  of  the  sensory 
nerve,     d,  The  nerve  trunk.    /,  The  sympathetic  nerve  ganglion  connected  with 
the  spinal  cord  through  the  white  and  the  gray  ramus  communicans.     e.  The 
neuraxis  of  the  sympathetic  neurone,     g,  Neuraxis  or  trunk  of  the  motor  neurone 
or  nerve  cell,     h,  The  anterior  horn  of  the  gray  matter  of  the  spinal  cord. 

7.  A  diagram  of  a  peripheral  sensory  neurone,     a,  The  neuraxis  which  ends 
in  the  spinal  cord  or  brain,     b,  The  T-shaped  division  of  Ranvier.     c,  The  den- 
drite or  sensory  nerve  fiber  in  the  nerve  trunk,     d,  The  nucleus  and  nucleolus 
of  the  cell  e.,  f.  the  axis  cylinder  process  of  the  cell,     g,  The  telodendrions  or 
terminal  branches  of  the  dendrite  or  axis  cylinder. 

8.  A  schematic  diagram  of  the  sensory  motor  reflex,     a,   The  telodendria. 
6,  The  dendrite.     c,  Nerve  cell  of  the  motor  neurone,     d,  The  motor  neurone. 
/,  The  muscle  fiber,     g,  The  neuraxis  of  both  sensory  and  motor  neurones,  the 
upper  being  the  sensory,     h,  the  nerve  cell  in  the  sensory  ganglion.     *,  The 
sensory  neurone  or  axis  cylinder  (nerve  fiber),     j.   The  skin  with  peripheral 
telodendrion  of  sensory  neurone. 


280  ANATOMY   OF   THE   DOMESTIC   FOWL 

The  bodies  of  cells  vary  in  size  from  4  to  100  microns  or  more  in 
diameter.  The  largest  cells  occur  in  the  inferior  horn  of  the  spinal 
cord,  in  the  spinal  ganglia,  in  the  large  pyramidal  cell  layer  of  the 
cerebral  cortex,  in  the  Purkinjean  pell  layer  of  the  cerebellum,  and 
in  Clark's  column  of  the  spinal  cord.  Very  small  cells  occur  in  the 
olfactory  bulbs,  in  the  granular  layer  of  the  cerebral  and  cerebellar 
cortex,  and  in  the  gliosum  cornuale  of  the  cord. 

Nerve  cells  are  classified  according  to  the  number  of  processes 
arising  from  the  cell  body,  and  neurones  are  referred  to  as  unipolar, 
bipolar,  and  multipolar. 

Unipolar  cells  are  met  with  frequently  in  early  stages  of  em- 
bryonic development,  but  are  rare  in  adults,  occurring  only  in  the 
retina,  in  the  olfactory  bulb,  and  within  the  baskets  of  the  Pur- 
kinjean cells  of  the  cerebellum.  The  cells  of  the  cerebro-spinal 
ganglia,  except  the  cochlear  and  vestibular,  are  apparently  uni- 
polar, but  they  are  developmentally  and  functionally  of  bipolar 
nature. 

Bipolar  cells  are  found  almost  exclusively  in  the  peripheral  sen- 
sory system,  as  in  the  olfactory  membrane,  in  the  retina,  in  the  coch- 
lear and  vestibular  ganglia,  and  in  the  cerebrospinal  ganglia  of  the 
embryo. 

Multipolar  cells  are  the  most  numerous  and  form  the  principal 
elements  of  nerve  centers  throughout  the  system.  They  are  termed 
multipolar  because  of  the  greater  or  lesser  number  of  dendrites 
given  off  in  addition  to  the  single  axone. 

The  body  of  the  nerve  cell  consists  of  a  mass  of  protoplasm  sur- 
rounding a  nucleus.  The  cytoplasm  of  the  nerve  cell  consists  of 
two  distinct  substances:  first,  neurofibrils;  second,  perifibrillar  sub- 
stance. In  most  nerve  cells  there  is  a  third  substance  called  chro- 
mophilic  bodies. 

The  neurofibrils,  extremely  delicate,  are  continuous  throughout 
the  cell  body  and  all  of  its  processes.  Within  the  body  of  the  cell 
they  cross  and  interlace  and  probably  anastomose. 

The  perifibrillar  substance  is  a  fluid  or  a  semifluid  substance  which 
both  in  the  cell  body  and  in  the  processes  surrounds  and  separates 
the  neurofibrils. 

The  chromophilic  bodies  are  granules  or  groups  of  granules  which 
occur  in  the  cytoplasm  of  all  the  larger  and  of  many  of  the  smaller 
nerve  cells. 


NEUROLOGY  281 

THE  SPINAL  NERVES 

The  first  pair  of  spinal  nerves  come  out  between  the  atlas  and -the 
occipital  bone.  Each  nerve  divides  into  three  branches.  The  first 
is  the  anterior  branch  which  innervates  the  dorsalis,  the  biventer 
cervicis,  the  cervicales,  and  the  caput  posticus  muscles.  The  sec- 
ond is  the  recurrent  ventralis  which  passes  mesially  and  downward 
from  the  recurrent  communicans.  It  innervates  the  rectus  capitis 
anticus  muscle  and  joins  a  branch  of  the  hypoglossal  nerve.  There 
is  given  off  a  white  ramus  communicans  to  the  sympathetic  nerve. 

The  second  spinal  nerve  emerges  from  the  opening  between  the 
first  and  the  second  cervical  vertebrae  and  is  similarly  disposed  as 
the  first  cervical.  It  gives  off  a  branch  called  the  recurrent  ventralis 
which  fuses  with  branches  of  the  first  cervical  and  the  hypoglossal 
nerve.  This  nerve  innervates  the  complexus  muscle. 

The  succeeding  cervical  nerves  emerge  in  a  similar  manner  down 
the  neck  and  are  distributed  to  the  muscles  and  other  structures  of 
the  cervical  region.  The  second,  the  third,  and  the  fourth  cervical 
nerve  gives  off  branches  which  form  anastomosing  loops  with  the 
facial  nerve. 

According  to  Gadow  the  last  cervical  nerve  passes  between  the 
last  cervical  and  the  first  dorsal  segment.  There  are  thus  fifteen 
pair  of  cervical  nerves. 

The  first  pair  of  dorsal  nerves  pass  out  between  the  first  two  dorsal 
vertebrae.  The  first  few  dorsal  nerve  branches  innervate  only  the 
trunk  muscles.  Other  branches  supply  the  skin  and  the  other 
adjacent  integument.  The  ventral  branches  of  the  cervical  nerves 
often  communicate  with  the  ventral  branches  of  the  first  dorsal 
nerves.  These  branches  are  larger  than  the  superior  branches  and 
aid  in  the  formation  of  the  bracial  plexus.  Smaller  inferior  branches 
are  distributed  to  the  scalenus  and  other  muscles,  and  extend  as  far 
posterior  as  the  intestines. 

The  dorsal  branches  of  the  spinal  nerves  in  the  lumbo-sacral 
region  are  very  small,  on  account  of  the  lack  of  extensive  develop- 
ment of  the  muscles  of  this  region.  The  elements  entering  into  these 
nerve  trunks  are  largely  vasomotor  nerves.  In  addition  to  the 
upper  twigs  supplying  the  skin  and  the  other  integument  of  the 
region,  other  branches  descend  into  the  abdominal  cavity. 

The  caudal  spinal  nerves  are  not  well  developed  and  disappear 
in  the  region  of  the  caudal  vertebrae.  The  dorsal  branches  inner- 


282  ANATOMY   OF   THE   DOMESTIC   FOWL 

vate  the  levator  muscles,  and  the  ventral  branches  the  depressor 
muscles. 

There  is  thus  given  off,  throughout  the  vertebral  column,  a  pair 
of  nerves  between  each  two  vertebral  segments,  making  as  many 
pairs  of  nerves  for  the  region  as  there  are  vertebral  segments  of 
that  region. 

The  Brachial  Plexus. — The  brachial  plexus  (Fig.  73,  No.  19) 
arises  principally  from  the  roots  of  the  last  three  cervical  and  the 
first  dorsal  spinal  nerves.  These  branches  anastomose  beneath  the 
deep  face  of  the  scapulo-humeral  articulation. 

The  brachial  plexus  divides  into  two  distinct  parts.  The  first 
(Fig.  73,  No.  20)  the  dorsal  called  the  superior  thoracic  is  distributed 
to  the  serratus  and  the  rhomboideus  muscle.  The  second  is  the 
inferior  thoracic  (Fig.  73,  No.  21),  which  consists  of  the  main  plexus, 
and  which  gives  off  muscular  branches  especially  to  the  sterno-cora- 
coideus  and  to  the  main  portion  passing  on  as  the  nerve  trunk  to 
the  structures  of  the  wing. 

From  the  superior  thoracic  plexus  there  are  several  secondary 
plexuses  formed. 

The  dorsalis  or  serratus  plexus.  This  plexus  is  located  adjacent 
to  the  anterior  part  of  the  main  plexus  and  is  formed  of  from  two 
to  four  spinal  nerve  branches.  The  rhomboideus  is  supplied  by 
branches  which  may  be  traced  to  the  first  root  of  this  plexus. 
This  nerve  is  called  the  rhomboideus  superficialis.  Another  nerve 
is  given  off  from  the  middle  part  of  the  dorsal  side  of  the  plexus 
and  is  called  the  rhomboideus  profundus.  A  third,  the  superficialis 
serratus,  is  the  largest  of  the  branches.  It  breaks  up  into  terminal 
branches,  one  going  to  each  serration,  or  digitation,  of  the  serratus 
muscle.  Branches  from  the  anterior  portion  of  this  plexus  are  dis- 
tributed to  the  patagii  muscles. 

The  superior  brachial  plexus  gives  off  the  following  nerves: 

The  subcoraco-scapularis,  which  is  purely  a  motor  nerve,  springs 
from  the  anterior  roots  of  the  plexus.  It  gives  off  a  branch  to  the 
following  three  muscles:  subcoracoideus,  subcoracoido-scapularis, 
and  scapulo-humeralis. 

The  scapulo-humeralis  is  distributed  to  the  scapular  humeral 
region. 

The  latissimus  dor  si  is  located  on  the  peripheral  border  of  the  scap- 
ulo-humeralis or  supra-spinatus.  It  originates  from  the  second, 
and  the  fourth  nerve  roots  of  the  plexus.  It  is  located  on  the  dorsal 


NEUROLOGY  283 

side  of  the  plexus.  It  divides  into  two  main  branches,  one  going 
to  the  latissimus  dorsi  and  the  other  to  the  scapulo-humeralis 
muscle.  From  the  side  are  given  off  branches  which  supply  the 
patagii  muscle  and  enter  into  the  formation  of  the  dorso-cutaneous 
plexus. 

The  axillaris  springs  from  the  second  and  the  third  root  of  the 
brachial  plexus,  extends  in  a  lateral  direction,  passing  the  ventral 
and  distal  rim  of  the  insertional  part  of  the  posterior  scapulo-hu- 
meralis or  teres  et  infraspinatus  and  enters  near  the  capsular  liga- 
ment of  the  shoulder -joint.  It  gives  off  to  this  joint  a  small  branch, 
called  the  recurrent  articularis,  which  passes  outward  between  the 
triceps  brachialis  and  the  humerus.  It  lies  on  the  inner  side  of  the 
major  deltoid,  and  patagii  muscles,  and  also  the  skin  of  the  lateral 
shoulder  and  the  upper  arm  region.  The  recurrent  axillaris  commu- 
nicates with  the  main  branch  of  the  radial  nerve. 

The  cutaneus  brachii  superior  is  a  small  nerve  which  springs 
from  the  last  brachial  plexus  root  and  passes  between  the  skin  and 
the  triceps  brachii  muscle  on  the  dorsal  surface  of  the  upper  arm, 
or  brachial,  region.  It  extends  down  over  the  elbow  region,  where 
it  gives  off  numerous  branches  to  the  skin  of  these  regions,  to  the 
meta-patagium  and  to  the  extensor  muscles  of  the  upper  arm. 

The  brachialis  longus  superior  is  a  large  nerve  trunk  which  springs 
from  most  of  the  other  plexus  roots.  It  extends  around  to  the 
dorsal  side  of  the  upper  arm  and  supplies  the  skin,  the  feathers,  and 
the  muscles  of  the  forearm  and  the  hand.  Branches  from  this  nerve 
trunk  supply  the  triceps  brachii  and  other  muscles  of  the  region. 
The  main  branch  passes  between  the  radius  and  the  ulna,  and,  pass- 
ing the  elbow-joint,  gives  off  branches  to  that  joint.  Passing  on,  it 
divides  into  two  branches.  One  of  these  extends  superficially  over 
the  upper  part  of  the  condylus  ulnaris  and  supplies  the  extensor 
digitorum  communis  and  the  extensor  metacarpi  ulnaris,  or  flexor 
metacarpi  radialis  muscles,  and,  continuing  superficially  to  the 
ulnar  side,  is  distributed  to  the  skin  of  the  region.  The  second,  a 
deep  branch,  extends  on  the  ulnar  side  of  the  radius  over  the  ex- 
tensor indicis  longus,  and  innervates  the  latter  muscle,  the  extensor 
pollicis  longus,  the  extensor  pollicis  brevis,  the  adductor  pollicis,  the 
interosseous  palmaris,  and  the  flexor  digitorum. 

The  inferior  brachial  plexus  gives  off  the  following  branches: 

The   supra-coracoideus,   a   large   nerve   which   springs  from  the 


284  ANATOMY    OF   THE   DOMESTIC   FOWL 

first  main  root  of  the  plexus,  and  passes  outward  through  the  fora- 
men coracoideum  of  the  sternal  ligament. 

The  sterno-coracoideus,  a  small  nerve  which  extends  downward 
from  the  plexus. 

The  somewhat  large  posterior  coraco-brachialis,  nerve  which 
springs  from  one  or  two  middle  roots  of  the  plexus  and  accompanies 
the  pectoral  nerve. 

The  anterior  thoracic,  a  large  nerve  which  springs  from  two  or 
three  of  the  posterior  roots  of  the  plexus  and  extends  to  the  shoulder 
cavity  where  it  branches.  The  anterior  branch  is  distributed  to 
the  patagium  and  the  front  part  of  the  pectoral  muscles.  The 
posterior  branch  supplies  muscles  along  the  side  of  the  thorax  and 
extends  into  the  abdominal  muscles. 

The  anterior  coraco-brachialis,  a  small  nerve  which  springs  mostly 
from  the  inferior  longus  brachialis,  passes  to  the  distal  end  of  the 
tuberculum  humeralis  radii,  then  passes  backward  between  the 
front  part -of  the  humerus  and  the  biceps,  where  it  supplies  the 
anterior  coraco-brachialis. 

The  cutaneous  brachialis  et  inferior  brachialis,  a  small  nerve  which 
springs  from  the  posterior  roots  of  the  plexus.  It  is  distributed  to 
the  skin  of  the  region  and  branches  are  given  off  to  the  patagii  and 
the  ventral  wing  surface.  A  few  branches  extend  as  far  as  the  upper 
arm. 

The  brachialis  longus  inferior  (Fig.  68,  No.  2) ,  a  continuation  of 
the  main  trunk  of  the  inferior  brachial  nerve,  which  comes  out  of 
all  the  plexus  roots  except  the  first.  It  gives  off  some  branches  to 
the  pectoral  region  and  then  enters  the  shoulder  cavity.  It  gives 
off  the  anterior  coraco-brachialis,  passes  down  the  humerus  in  an 
S-shape,  and  divides  into  two  branches,  the  ulnar  and  the  median. 

The  ulnar  nerve  (Fig.  67,  No.  3)  divides  into  numerous  branches 
which  are  distributed  to  the  ulnar  side  of  the  forearm  and  the  hand. 
The  ulnar  nerve  passes  below,  the  skin  of  the  ulnar  outside  rim  of  the 
forearm  and  gives  branches  to  the  carpi  ulnaris,  finally  supplying 
the  flexor  digitorum;  it  then  passes  with  the  tendon  of  this  muscle 
downward  to  the  interosseous  dorsalis,  the  abductor  indicis,  or 
flexor  minimi  brevis,  the  flexor  pollicis,  and  the  abductor  pollicis, 
or  extensor  proprius  pollicis. 

The  median  nerve  (Fig.  67,  No.  2)  extends  down  the  arm  and  gives 
branches  to  the  biceps  muscle,  and  to  the  patagii  region.  Continu- 
ing, the  median  nerve  supplies  the  pronator  muscle  and  the  brachi- 


NEUROLOGY  285 

alis  inferior,  or  brachialis  anticus,  and  then  divides  into  two  branches. 
The  first  and  largest  branch  passes  between  the  two  pronator  muscles 
giving  branches  to  the  pronator  profundus,  or  pronator  longus,  and 
the  flexor  digitorum  profundus  muscle.  This  nerve  then  passes 
anteriorly  along  the  tendon  to  the  base  of  the  digit,  and,  on  the 
dorsal  side,  joins  the  other  branch  of  the  median  nerve.  At  this 
point  there  is  often  a  plexus,  and  at  the  point  of  fusion  of  the  ulnar 
nerve  on  the  ulnar  side  there  may  also- be  a  small  plexus.  These 
plexuses  mainly  supply  the  skin  of  these  regions.  The  second 
branch,  passes  forward,  crosses  the  extensor  carpi  radialis  and  lies 
just  below  the  pronator  profundus,  or  pronator  longus,  giving 
branches  to  the  skin.  It  passes  downward  on  the  radial  side  of  the 
ulnar  and  supplies  the  muscles  of  that  part;  it  then  continues 
down  the  hand.  Branches  are  given  off  to  the  extensor  proprius 
pollicis,  the  interosseous  dorsalis,  the  flexor  digitorum,  and  to  the 
skin  between  the  thumb  and  the  forefinger. 

The  intercostal  nerves  (Fig.  70,  No.  18)  are  given  off  from  the 
spinal  cord  of  the  dorsal  region.  The  superior  branches  are  small 
and  supply  the  superior  dorsal  region.  The  inferior  branches  lie 
one  behind  each  rib,  innervate  the  intercostal  muscles,  and  give 
a  few  twigs  to  the  superficial  thoracic  muscles. 

The  Lumbo-sacral,  or  Crural,  Nerve  Plexus. — The  crural  plexus 
(Fig.  70,  No.  35  and  36)  is  made  up  of  trunks  from  the  last  two 
lumbar  and  first  four  sacral  spinal  nerves.  There  are  two  portions 
of  this  plexus  separated  by  a  considerable  distance. 

The  anterior  portion  (Fig.  70,  No.  35)  consists  of  the  lumbar 
nerves  and  a  portion  of  the  first  sacral  nerves.  The  fusion  takes 
place  on  the  bony  ridge  that  separates  the  lumbar  from  the  sacral 
region. 

The  posterior  portion  (Fig.  70,  No.  36)  consists  of  a  part  of  the 
first  sacral  and  all  of  the  three  succeeding  nerves. 

The  anterior  nerve  of  this  plexus  is  distributed  to  the  abdominal 
muscles.  An  anterior  branch  is  given  off  to  the  sartorius.  A  large 
cutaneous  branch  enters  between  the  sartorius  and  the  ilio-trochan- 
teric  eminence,  and  supplies  the  outer  and  the  upper  surface  of  the 
upper  thigh  region.  Several  short  branches  are  given  off  from  the 
middle,  or  main,  mass  of  the  crural  plexus  to  the  ilio-trochanteric, 
or  gluteal,  muscle.  Another  nerve  passes  over  the  side  of  the 
sartorius  adjacent  to  the  femoro-tibialis,  or  extensor  femoris, 
and  supplies  the  ilio-tibialis,  or  gluteus  primus.  The  rest  of  this 


286  ANATOMY   OF  THE  DOMESTIC  FOWL 

section  of  the  crural  nerves  pass  in  a  distal  direction  over  the  inner 
and  front  side  of  the  cutaneous  nerve  and  enter  the  ilio-femoralis, 
or  gluteus  medius,  the  ambiens  and  the  femoro-tibialis  muscle. 

The  furcalis  nerve  comes  out  between  the  lasttwo  lumbo-sacral 
vertebrae. 

The  obturator  nerve  springs  from  several  roots.  The  anterior  root 
of  this  nerve  comes  from  the  main  trunk  of  the  crural  plexus,  and 
its  last  root  from  the  furcalis  nerve.  The  obturator  nerve  extends 
in  a  ventral  direction  from  the  plexus,  then  horizontally  on  the  inner 
surface  of  the  abdominal  cavity.  It  gives  off  twigs  to  the  obturator 
muscle  and  then  passes  through  the  obturator  foramen.  After  leav- 
ing the  abdominal  cavity  it  gives  branches  to  the  accessorius,  the 
obturator,  and,  the  pubio-femoral,  or  adductor  longus  muscle. 

The  crural  plexus  gives  off  another  large  nerve  trunk  which  ex- 
tends downward.  Shortly  after  emerging  from  the  plexus  it  gives 
off  a  muscular  branch  to  the  ilio-femoralis,  or  gluteus  medius 
muscle.  It  then  passes  between  this  muscle  and  the  shaft  of  the 
femur,  to  the  inner  posterior  surface  of  the  thigh,  and  to  the  inner 
surface  of  the  knee.  It  gives  off  a  branch  to  the  structures  of  the 
knee.  At  the  knee  this  nerve  terminates  in  several  branches,  some 
of  which  pass  to  the  inner  surface  of  the  tibial  head,  the  internal 
lateral  ligament,  the  periosteum,  the  internal  condyle,  and  finally 
to  the  upper  part  of  the  head  of  the  gastrocnemius  muscle. 

The  main  part  of  this  nerve  passes  downward  as  the  cutaneous 
nerve,  along  the  inner  surface  of  the  lower  thigh. 

The  ischiadic  plexus  (Fig.  64,  No.  41)  has  five  to  six  roots,  which 
fuse  into  the  ischiadic  trunk.  This  main  trunk  extends  out  of  the 
abdominal  cavity,  through  the  ischiadic  foramen,  close  behind  the 
anterior  trochanter  of  the  ilium  (Fig.  65,  No.  i).  It  gives  a  branch 
to  the  external  ilio-femoral  or  gluteus  medius,  and  a  branch  to  the 
post-acetabular  portion  of  the  ilio-tibialis,  or  gluteus  primus 
muscle.  The  main  trunk  (Fig.  69,  No.  13)  passes  downward  to  the 
lower  portion  of  the  thigh.  In  this  course  there  are  two  branches 
which  run  parallel  to  the  femoral  artery  and  the  femoral  vein.  It 
gives  off  a  small  muscular  branch  to  the  accessorius,  and  further 
down  gives  off  a  long  slender  branch  to  the  outside  of  the  knee- 
joint.  It  gives  off  a  lateral  cutaneous  branch  (Fig.  66,  No.  7)  to 
the  posterior  outer  portion  of  the  lower  thigh.  It  supplies  motor 
fibers  to  the  external  head  of  the  gastrocnemius  muscle. 

At  the  knee  region  the  ischiadica  divides  into  three  parts.     The 


NEUROLOGY  287 

largest  branch  (Fig.  69,  No.  14)  passes  with  the  tendon  of  the  ilio- 
fibularis,  or  biceps  femoris  muscle,  through  a  loop,  the  biceps  band, 
and  lies  on  the  upper  lateral  surface  of  the  fibula.  It  is  covered 
by  the  external  head  of  the  gastrocnemius  muscle.  It  innervates 
the  three  posterior  muscles  of  the  lower  thigh,  and  then  divides  into 
two  branches.  One,  the  superficialis  peroneus  (Fig.  69,  No.  16) 
passes  with  the  profundus  nerve,  forming  a  double  trunk  and 
occupying  the  tibio-fibular  groove  on  the  antero-lateral  side.  It 
passes  over  the  transverse  ligament  and  the  tibio-metatarsal  joint, 
and  after  sending  small  branches  to  the  structures  of  the  tibial 
side  of  the  metatarsus,  it  ends  as  a  cutaneous  nerve  on  the  upper 
side  of  the  third  and  the  fourth  toe. 

The  other  branch  is  the  peroneus  profundus,  which  separates  from 
the  peroneus  superficialis  and  passes  downward  in  company  with 
the  tendons,  under  the  transverse  ligament,  and  then  along  the 
anterior  upper  surface  of  the  metatarsus,  where  it  innervates  the 
muscles  of  that  region.  It  gives  branches  to  the  malleolus,  to  the 
tendons  of  the  third  toe,  and  to  the  median  part  of  the  second  toe, 
and  supplies  the  cutaneous  structures  of  the  third  and  the  fourth  toe. 

The  third  branch  of  the  ischiadica,  a  long  nerve,  is  given  off  just 
after  the  ischiadica  passes  through  the  loop.  It  passes  downward 
between  the  two  peroneal  nerves.  It  is  covered  by  a  sheath.  It 
passes  over  the  posterior  outside  rim  of  the  intertarsal  joint  and 
innervates  the  tendon  sheath.  The  main  portion  of  this  nerve  is 
located  on  the  anterior  surface  of  the  tendon  Achillis,  and  passes 
down  on  the  plantar  side,  and  innervates  the  periosteum  and  all 
plantar  foot  muscles.  It  finally  radiates  to  the  plantar  surface  of 
the  three  anterior  toes. 

The  integument  of  the  toes  is  sparingly  supplied  with  nerves. 

The  nerve  trunks  that  do  not  pass  through  the  biceps  band,  or 
loop  can  be  divided  into  a  medial  (Fig.  69,  No.  15)  and  a  lateral 
(Fig.  69,  No.  17)  portion.  The  medial  portion  (Fig.  69,  No.  15) 
soon  divides  into  numerous  branches  which  supply  the  muscles 
of  the  posterior  and  the  inner  portion  of  the  thigh.  A  rather  large, 
long  branch  passes  downward  along  the  tendon  of  the  plantar  mus- 
cle, which  lies  on  the  posterior  median  edge  of  the  tibia,  and  gives 
off  twigs  to  the  median  and  posterior  part  of  the  intertarsal  joint, 
supplying  the  periosteum  and  other  structures  and  the  adjacent 
skin.  It  passes  downward  along  the  outer  side  of  the  medial  meta- 
tarsal  insertion  of  the  tendon  Achillis. 


288  ANATOMY   OF   THE   DOMESTIC   FOWL 

The  fifth  branch  is  given  off  from  the  second  trunk  and  lies  later- 
ally. It  is  covered  by  the  external  head  of  the  gastrocnemius, 
passes  along  the  vena  saphena,  and  gives  off  a  short  main  branch 
to  the  inner  side  of  the  intertarsal  joint.  The  main  part  passes 
the  tibial  side  of  the  joint,  becomes  subcutaneous,  and  finally 
innervates  the  two  plantar  muscles.  A  lateral  ascending  inner 
branch  innervates  the  flexor  perforatus  digitorum,  and,  in  company 
with  an  outer  branch,  the  external  head  of  the  gastrocnemius,  and 
also  the  flexor  pedis  perforatus. 

The  plexus  pedundus  is  formed  from  the  spinal  nerves  coming  out 
of  the  plexus  ischiadicus.  These  fibers  emerge  caudalward  and 
are  directed  horizontally.  They  frequently  anastomose  with  each 
other,  especially  on  the  pubic  rim  and  on  the  outside  of  the  plexus 
ischiadicus.  These  branches  are  deeply  imbedded  in  the  kidney 
substance  and  innervate  the  pubio-coccygeus,  or  depressor  coccygis 
lateralis,  the  ilio-coccygeus,  the  transversalis,  the  sphincter,  and 
other  muscles  of  this  region,  and  the  skin  of  the  anal  region. 

THE  BRAIN 

The  Brain  Coverings. — The  cerebro-spinal  axis  of  birds  is  similar 
to  that  of  mammals.  The  meninges  of  the  brain  are  three  in  number, 
dura  mater,  arachnoid,  and  pia  mater.  The  dura  mater  is  the 
thickest.  It  is  constructed  of  white  fibrous  connective  tissue,  and 
lines  the  cranial  cavity.  Thus  it  serves  as  an  internal  periosteum. 
It  is  continuous  with  the  spinal  dura  mater  at  the  foramen  magnum, 
and  is  also  prolonged  as  a  sheath  of  the  nerves.  In  birds  of  flight 
where  the  air  sacs  and  reservoirs  are  developed  to  the  highest 
state,  Sappy  finds  that,  "  just  as  the  medullary  tissue  is  replaced  by 
air  in  the  bones  of  birds,  so  might  it  be  imagined  that  the  sub-arach- 
noid fluid  is  also  replaced  by  air  around  the  spinal  cord,"  and  ob- 
servations justify  the  correctness  of  this  statement.  The  .dura 
mater  measures  exactly  the  volume  of  the  marrow  in  birds;  so  that 
there  does  not  exist  between  the  fibers  and  the  nervous  surface 
any  space  for  an  accumulation  of  liquid.  This  anatomical  fact  is 
sufficient  to  demonstrate  the  absence  of  subarachnoid  fluid  in  the 
bird.  In  denying  the  existence  of  this  fluid,  it  ought  to  be  added 
that  in  this  class  of  vertebrates,  the  spinal  prolongation  is  covered 
by  a  triple  envelope;  and  that  between  the  pia  mater  and  the  dura 
mater  is  a  thin  transparent  membrane,  which  is  lubricated  by  a 


NEUROLOGY  289 

serous  fluid.     This  fluid  however  does  not  collect;  it  only  moistens 
the  arachnoid  membrane. 

The  arachnoid  is  located  between  the  dura  mater  above  and  the 
pia  mater  below.  The  pia  mater  adheres  closely  to  the  nerve 
tissue. 

The  falx  cerebri  exists  in  fowls  and  in  turkeys.  It  has  the  form  of 
a  segment  of  a  circle,  and  extends  from  the  middle  of  the  interval 
of  the  openings  for  the  olfactory  nerves  to  the  tentorium  cerebelli. 
The  falx  cerebelli  is  absent.  The  tentorium  is  small  and  is  sustained 
by  a  bony  plate,  and  there  are  in  addition  two  folds,  one  on  each 
side,  that  separate  the  hemispheres  from  the  tubercula  quadrigemina. 
Owing  to  the  absence  of  the  falx  cerebelli,  the  meninges  lie  close 
together.  The  falx  cerebri  is  ossified  in  birds. 

The  Brain  Structure. — The  brain  (Fig.  62,  C  and  Fig.  75,  A  and 
C)  is  made  up  of  three  principal  parts:  the  cerebrum,  the  cere- 
bellum and  the  medulla  oblongata.  In  a  fowl  of  medium  size  the 
brain  weighs  about  150  grains. 

The  pons  varolii  is  absent  in  birds.  The  crura  cerebelli  (Fig. 
75,  No.  9)  are  immediately  connected  with  the  corpora  restiformia. 
The  lower  face  of  the  isthmus  is  convex  posteriorly;  in  front,  the 
tubercula  bigemina  (Fig.  75,  No.  4)  are  united  to  each  other  by  a 
comparatively  large  transverse  cord,  formed  by  the  optic  nerves 
intercrossing  in  the  median  line.  The  superior  face  of  the  medulla 
oblongata  is  depressed  above  to  constitute  a  fourth  ventricle;  in 
front  of  this  ventricle  are  the  tubercula  bigemina,  or  optic  lobes. 
These  two  voluminous  tubercles  are  separated  from  each  other  above, 
where  they  embrace  the  cerebellum,  and  are  salient  on  the  sides  of 
the  lower  face.  They  are  hollow  internally,  and  communicate 
with  the  aqueduct  of  Sylvius.  The  thalami  optici  are  not  well 
developed. 

A  large  transverse  fissure  divides  the  cerebrum  from  the  cerebellum 
(Fig.  75,  No.  5).  The  optic  chiasm  (Fig.  75,  No.  15)  behind  which 
lies  the  hypophysis  (Fig.  62,  No.  C,  20)  covers  the  region  of  the  middle 
brain.  The  large  transverse  fissure  is  the  dividing  line  between  the 
hemispheres  and  the  optic  lobes.  If  the  hypophysis  be  removed 
there  will  be  observed  a  slit  surrounded  by  gray  matter  which  is 
called  the  tuber  cinereum  et  infundibulum  (Fig.  75,  No.  18). 
On  the  pars  commissuralis  and  the  after  brain  there  are  visible  the 
roots  of  the  fifth,  the  ninth,  the  tenth,  and  the  twelfth  pairs  of 
cranial  nerves.  Close  beside  the  median  furrow  which  extends  to 

19 


2 go  ANATOMY    OF    THE   DOMESTIC   FOWL 

the  front  part  of  the  long  furrow  of  the  spinal  cord  there  is  observed 
the  third  pair  of  cranial  nerves,  which  have  their  origin  in  the  middle 
brain.  The  fourth  pair  of  cranial  nerves  extend  from  the  roof  of  the 
middle  brain  on  both  sides  between  the  middle  brain  and  the  optic 
lobes.  These  nerves  finally  emerge  and  become  visible  on  the 
ventral  surface. 

The  sixth  nerve  is  visible  near  the  middle  furrow  and  almost  in 
the  middle  of  the  pyramids,  and  near  the  roots  of  the  fifth,  the 
seventh,  the  ninth,  the  tenth,  and  the  twelfth  pair  of  cranial  nerves. 

THE  DIVISIONS  OF  THE  BRAIN 

Thalamus 
Pineal  body 
Infundibulum 
Hypophysis 


Forebrain 


Midbrain 


Optic  tract  and  chiasm 
Cerebral  hemispheres 
Olfactory  lobes 
Third  ventricle 
lateral  ventricles 
Peduncles  of  the  cerebrum 
Optic  lobes 


Aqueduct 
f  Medulla  oblongata 
Hindbrain       Cerebellum 

[  Fourth  ventricle 

The  medulla  oblongata  (Fig.  62,  No.  C,  i;  Fig.  75,  A  and  C)  termi- 
nates anteriorly  in  the  pars  commissuralis  and  the  pars  peduncularis. 
As  the  spinal  cord  approaches  the  head  there  is  a  gradual  swelling,. 
or  lateral  thickening,  which  merges  into  the  medulla  oblongata. 
The  superior  and  the  inferior  surface  of  the  medulla  oblongata  (Fig. 
75,  No.  A,  i  and  C,  17)  are  flattened.  There  is  a  shallow  furrow  and  a 
slight  swelling  at  the  point  where  the  hypoglossal  nerve  emerges. 
The  central  canal  of  the  spinal  cord  gradually  comes  closer  to  the 
upper  surface  and  communicates  with  the  fourth  ventricle,  at  which 
point  the  posterior  raphe  is  shortened  and  the  sulcus  longitudinalis 
posterior  becomes  shallow.  At  the  point  where  the  central  canal 
terminates  in  the  fourth  ventricle  there  is  a  V-shaped  point  called 
the  calamus  scriptorius  (Fig.  75,  No.  2).  The  fourth  ventricle  is 
located  on  the  upper  wall  of  the  medulla  oblongata  below  the  cere- 
bellum, and  is  bounded  laterally  by  the  peduncles  of  the  cerebellum. 
It  is  marked  posteriorly  by  the  calamus  scriptorius  and  anteriorly 
by  the  valve  of  Vieussens. 


NEUROLOGY  2QI 

The  valve  of  Vieussens  is  located  at  the  posterior  end  of  the  aque- 
duct of  Sylvius.  The  posterior  part  of  the  fourth  ventricle  is  marked 
by  grooves  or  furrows.  Extending  along  the  central  part  of  the 
floor  of  the  fourth  ventricle  there  is  a  sulcus,  or  groove,  called  the 
sulcus  centralis,  which  divides  the  superior  pyramids.  On  the 
median  lateral  sides  there  are  two  points  of  gray  substance  which 
form  the  alae  cinereae.  The  roots  of  the  pneumogastric,  the  glosso- 
pharyngeal,  and  the  spinal  accessory  may  be  traced  to  the  alae 
cinereae  and  the  gray  matter  of  the  ridges  of  the  medulla  oblongata. 
The  sixth  pair  of  the  cranial  nerves  emerge  from  the  medulla  near 
the  sulcus  centralis  and  to  the  side  of  the  auditory  nerve.  Part 
of  the  trigeminus  emerges  from  the  rim  of  the  furrow  next  to  the 
ridge.  At  the  outer  border  of  the  medulla  are  observed  the  thick 
ends  of  the  roots  of  the  pneumogastric,  the  spinal  accessory,  the 
glosso-pharyngeal,  and  the  auditory  facialis.  * 

On  both  sides  of  the  sulcus  longitudinalis  inferior  are  found  the 
inferior  pyramids,  or  pyramidal  columns.  These  pyramids  become 
expanded  near  the  origin  of  the  third  pair  of  nerves  and  merge  into 
the  cerebral  peduncles,  or  crura  cerebri. 

The  pyramidal  fibers  may  also  be  traced  to  the  optic  lobes.  The 
roots  of  the  abducens  are  found  at  a  point  between  the  crura  cerebri 
and  the  optic  lobes.  The  third  pair  lies  to  the  side  of  this,  and  the 
roots  of  the  trigeminus  are  adjacent  to  those  of  the  third.  A 
bundle  of  fibers  from  this  region  pass  into  the  cerebellum  and  form 
the  crura  cerebelli;  others  pass  into  the  cerebellum  from  the  side, 
spreading  out  in  fan-shaped  radiation,  and  forming  the  white  central 
substances  peculiarly  arranged,  called  the  arbor  vitas,  or  tree  of  life. 
A  third  bundle  fuse  with  the  crura  cerebelli  anteriorly,  and  pass 
into  the  peduncles  of  the  cerebrum,  or  crura  cerebri. 

The  gray  ganglionic  substance  forms  columns  which  extend  the 
whole  length  of  the  medulla  oblongata  and  into  the  cerebri.  The 
medulla  oblongata  contains  numerous  centers  which  preside  over 
various  visceral  functions  as  deglutition,  respiration ,  thermotactic, 
secretory,  cardiac,  and  digestion. 

In  the  medulla  as  in  the  spinal  cord  there  are  five  main  groups 
of  cells.  First,  the  posterior  or  upper  horns,  from  which  come  the 
somatic  sensory  nerves.  Second,  Clark's  cells,  located  centrally, 
which  are  the  origin  of  the  ganglionated  splanchnic  nerves.  Third, 
cell  groups  of  the  lateral  horns  which  are  the  center  for  the  non- 
ganglionated  splanchnic  nerves,  and  certain  other  nerves  for  the 


2Q2 


ANATOMY   OP   THE   DOMESTIC   FOWL 


viscera,  including  the  enteric  muscles.  Fourth,  cell  groups  of  the 
anterior  horns,  which  are  the  center  of  all  somatic  voluntary 
muscles.  Fifth,  groups  of  single  cells  probably  belonging  to  the 


FIG.  77,  A. 

G,  A  section  through  the  tuberculum  bigeminum.  i,  Pia  mater.  2,  Nerve 
fibers.  3,  Fine  granular  ground  substance.  4,  Thin  layer  of  small  cells.  5, 
Fine  granular  ground  substance.  6,  A  second  tljin  cell  layer.  7,  Fine  granular 
ground  substance.  8,  Third  thin  cell  layer.  9,  Fine  granular  ground  substance. 
10,  Fourth  widely  extended  cell  layer,  n,  A  fine  granular  layer.  12,  A  thick 
layer  of  spindle  cells.  13,  A  layer  of  medullated  nerve  fibers.  14,  Ependemal 
cells.  15,  The  sinus. 

H,  A  transverse  section  through  the  medulla  oblongata.  i,  3,  4  and  6  are 
ganglionic  centers.  2,  The  dorsal  groove.  8,  The  ventral  fissure.  5,  The  central 
canal.  7,  Fiber  tracts. 

7,  A  transverse  section  through  the  cervical  portion  of  the  spinal  cord,  i, 
Ventral  septum.  2,  Dorsal  septum.  3,  The  central  canal.  4,  The  dorsal  horn. 
5,  The  ventral  horn. 

J,  A  section  through  the  wall  of  the  oil  gland,  or  rump  gland,  i,  The  stroma. 
2,  The  tubular  glands  some  of  which  are  branched. 

K,  A  section  through  a  spike  of  a  comb  of  a  cock,  i,  The  epithelial  layer.  2, 
A  dense  fibrous  subepithelial  layer.  3,  A  second  fibrous  vascular  layer.  6,  A 
denser  central  core  supporting  the  large  arteries  and  veins.  4,  A  vein.  5,  An 
artery. 

L,  A  section  through  a  lobe  of  the  wattle  of  a  hen.  i,  The  epithelial  layer. 
2,  A  dense  vascular  layer.  3,  A  vein.  4,  An  artery.  5,  A  loose  fibrous  vascular 
structure. 

posterior  horns  which  are  probably  centers  for  other  splanchnic 
nerve  fibers. 

The  gray  matter  in  the  cord  is  in  the  form  of  two  commas  placed 
with  their  backs  together  with  the  central  canal  passing  between 


NEUROLOGY  293 

them.  The  central  canal  is  located  in  the  center  of  the  cord.  As 
the  cord  nears  the  medulla  oblongata  the  form  of  the  gray  matter 
changes.  The  second,  the  third,  and  the  fifth  ganglion  centers"are 
arranged  laterally,  and  show  a  distinct  side-horn  group.  The 
central  canal  separates  the  two  Clark's  columns;  later  the  side-horn 
group  enlarges  and  extends  ventrally  around  the  anterior  horn  group 
and  joins  on  the  other  side  in  half-moon  shaped  formation. 

The  central  ganglionic  mass  of  the  spinal  cord,  the  center  for  the 
enteric  visceral  system,  is  divided  into  three  complex  parts.  First, 
there  are  cell  groups  on  both  sides  of  the  posterior  raphe.  Second, 
the  half -moon  shaped  ventral  groups  extending  parallel  peripherally 
described  above.  Third,  lying  between  groups  one  and  two  a  com- 
plex group,  which  possesses  a  large  collection  of  cells.  These  fur- 
nish splanchnic  nerve  centers,  the  anterior  supplying  motor  nerves 
and  carrying  motor  impulses  outward,  and  the  superior  sensory 
which  carry  impulses  to  the  centers.  The  cell  group  of  the  superior 
horns  takes  a  sidewise  peripheral  position  (Gadow). 

The  cerebellum  (Fig.  62,  C,  2)  is  located  above  the  medulla  oblon- 
gata and  posterior  to  the  cerebrum.  The  cerebellum  consists  prin- 
cipally of  a  median  lobe  called  the  worm.  The  lateral  lobes  are 
conical  and  rudimentary.  The  under  part  of  the  worm  forms  the 
roof  of  the  fourth  ventricle. 

On  the  upper  surface  of  the  cerebellum  are  numerous  transverse 
markings  (in  the  hen  13  or  14)  which  divide  the  lobe  into  leaves. 
When  the  cerebellum  is  cut  lengthwise  there  is  observed  on  the 
sectioned  surface  the  peculiar  arrangement  of  the  white  and  the 
gray  matter,  the  arbor  vitae,  mentioned  above.  There  is  a  small 
cavity  in  the  cerebellum  which  communicates  with  the  fourth 
ventricle. 

The  cerebellar  cortex  shows  four  parts,  namely:  First,  the  central 
part  composed  of  white  medullated  fibers,  between  which  are 
arranged  neuroglear  cells.  Second,  a  rather  reddish  layer  of  cells 
of  different  sizes.  These  cells  are  embedded  in  a  fine  ground 
substance  and  are  about  0.003  mm-  m  diameter.  Third,  a  plain 
layer  of  large  pear-shaped  ganglion  cells,  the  cells  of  Purkinje. 
Fine  branches  extend  outward  from  the  apex  of  these  cells.  Fourth, 
an  outer  gray  layer  which  consists  of  small  multipolar  nerve  cells 
with  some  neuroglear  cells.  The  color  of  these  three  layers,  accord- 
ing to  Gadow,  depends  upon  the  color  of  the  plumage;  that  is,  if 
the  plumage  is  dark,  this  layer  is  dark;  if  light,  the  layers  are 


2 94  ANATOMY   OF   THE   DOMESTIC   FOWL 

light.  The  marked  coloring  is  said  to  be  most  distinct  in  the 
second  layer. 

The  anterior  portion  of  the  cerebellum  consists  of  medullated 
nerves  whose  fibers  run  crosswise.  These  are  the  extensions  of  the 
true  cerebellar  fibers,  which  become  fewer  and  fewer  as  they  proceed 
anteriorly.  Finally,  a  few  remaining  fibers  running  crosswise  fuse 
as  the  commissura  Sylvii,  and  extend  into  the  lobi  optici.  A  layer 
of  nerve  cells  extends  under  these  medullated  nerve  fibers. 

A  bundle  of  fibers  extending  from  the  medulla  oblongata.  These 
fibers  extend  into  the  optic  lobes,  form  the  crura  cerebri,  or 
peduncles  of  the  cerebri,  and  also  form  the  inferior  wall,  or  floor, 
of  the  aqueduct  of  Sylvius.  The  crura  are  sometimes  spoken  of  as 
the  partes  pedunculares.  These  contain  gray  matter.  The  follow- 
ing division  is  made  of  the  ganglion  of  this  region.  First,  a  group  of 
cells  near  the  base  of  the  peduncles,  which  are  divided  from  the 
ventral  rim  by  the  arciform  fibers.  This  ganglionic  formation  may 
be  considered  an  extension  from  the  medulla  oblongata.  Second, 
a  group  of  the  ganglion  cells  of  the  lobus  optici.  Third,  a  group 
of  cells  lying  near  the  lobus  opticus,  which  give  rise  to  the  ascending 
roots  of  the  trigeminus.  Fourth,  a  group  of  ganglionic  cells  from 
which  spring  the  roots  of  the  motores  occuli,  and  which  lies  near 
the  middle  line  and  under  the  sulcus  centralis.  Many  ganglion 
cells  are  found  to  the  right  and  to  the  left  of  the  sulcus  centralis, 
which  show  different  arrangement  of  the  cells  at  different  levels. 
Fifth,  a  group  of  irregular  cells  which  extends  centrally  on  the 
superior  walls  of  the  third  ventricle  andjto  the  superior  part  of  the 
lobus  opticus. 

The  microscopic  structure  of  the  roof  of  the  lobus  opticus,  or 
corpus  bigeminum,  shows  that  the  layers  are  arranged  parallel  to 
the  pia  mater  and  are  divided  into  the  following  parts : 

Externally,  the  pia  mater. 

An  outer  layer  of  very  fine  nerve  fibers,  which  lies  just  below  the 
pia  mater. 

A  layer  of  fine  granular  ground  substance. 

A  thin  layer  of  small  cells  the  diameter  of  each  of  which  is  0.038 
mm. 

A  layer  of  fine  granular  ground  substance. 

A  second  thin  cell  layer. 

A  zone  of  fine  granular  ground  substance. 

A  third  thin  cell  layer. 


NEUROLOGY  2Q5 

A  fine  granular  ground  substance. 

A  fourth  widely  extended  cell  layer. 

A  fine  granular  layer. 

A  somewhat  thick  layer  of  spindle-shaped  cells. 

A  layer  of  medulla  ted  nerve  fibers. 

This  last  is  the  inner  layer  of  nerve  fiber.  On  the  inner  surface 
of  this  layer  we  find  the  ependymal  cells,  the  cells  that  line  the  cavity 
of  the  optic  lobes.  The  commissura  Sylvii  form  the  covering  of  the 
lobi  optici  and  join  these  two  lobes.  This  commissure  is  formed 
from  the  upper  and  the  lower  layer  of  nerve  fibers.  In  the  commis- 
sure these  fibers  cross  each  other. 

The  hypophysis  (Fig.  62,  No.  C,  20)  lies  back  of  the  chiasm,  or 
optic  commissure,  and  below  the  middle  of  the  third  ventricle.  The 
infundibulum,  a  pedicle-like  structure,  connects  the  hypophysis  with 
the  third  ventricle  of  the  cerebri.  It  contains  a  cavity  and  forms 
an  extension  of  the  third  ventricle.  The  hypophysis  is  divided  into 
two  lobes,  an  anterior  and  a  posterior. 

The  third  ventricle  communicates  anteriorly  with  the  lateral 
ventricles  of  the  cerebri  through  the  foramen  of  Monro,  and  pos- 
teriorly -with  the  fourth  ventricle  through  the  aqueduct  of  Sylvius. 
The  posterior  walls  of  the  third  ventricle  are  relatively  thick  and 
form  the  posterior  brain  commissure.  The  wall  is  thin  from  the 
commissure  to  the  chiasm.  Within  it  lie  two  ridges,  which  connect 
the  two  hemispheres  with  the  corpus  callosum,  and,  farther  ante- 
riorly, with  the  anterior  cerebral  commissure.  The  space  from 
the  third  ventricle  and  to  the  anterior  commissure  is  called  the 
laminae  terminales. 

The  pineal  gland,  located  between  the  cerebri  and  the  cerebellum, 
lies  against  the  choroid  plexus,  which  covers  the  highest  point  of 
the  third  ventricle. 

The  cerebrum  is  divided  by  a  deep  longitudinal  fissure  into  two 
hemispheres.  The  cerebrum  is  shaped  somewhat  like  the  heart  on 
a  playing  card.  The  lower  face  is  somewhat  flattened.  The  upper 
and  lateral  sides  are  not  provided  with  convolutions  or  sulci,  but 
are  smooth.  The  fissure  of  Sylvius  is  faintly  marked  on  the  inferior 
face.  The  olfactory  lobes  appear  well  developed  and  are  relatively 
large  for  the  size  of  the  brain.  They  lie  close  together  on  the  extreme 
anterior  portion  in  the  median  line. 

The  olfactory  cerebral  crura  emerge  from  the  cranium  at  the 
upper  angle  between  the  posterior  wall,  the  roof,  and  the  septum  of 


2p6  ANATOMY   OF    THE   DOMESTIC   FOWL 

the  orbit,  and  pass  through  the  olfactory  foramina  and  in  grooves 
on  the  upper  part  of  the  septum ;  then  passing  forward  they  pene- 
trate the  frontal  structure  and  are  finally  distributed  over  the 
turbinated  mucous  membrane. 

The  corpus  striatum  is  large;  it  occupies  nearly  the  entire  floor 
of  the  ventricles. 

The  anterior  commissure  is  found  between  the  hemispheres.  Its 
middle  part  lies  in  the  lamina  terminalis  on  the  division  between 
the  anterior  and  the  middle  brain,  and  close  to  the  thalami  optici. 
Its  side  extensions  are  rounded  masses  called  the  nervi  amygdales. 

The  corpus  callosum,  quite  rudimentary,  lies  on  the  posterior 
dorsal  rim  of  the  anterior  commissure. 

The  corpus  striatum  forms  a  thin  broad  ridge,  which  passes  ven- 
trally.  This  structure  consists  of  twenty-five  large  pyramidal  cells 
which  lie  in  the  posterior  lateral  dorsal  section,  and  of  from  ten  to 
fifteen  pyramidal  cells  which  are  located  in  the  rest  of  the  section. 
In  addition  to  these  two  groups  there  are  many  cells  about  5  milli- 
meters in  diameter.  These  lie,  six  or  more,  in  a  nest  imbedded  in 
neuroglia.  There  is  a  thin  layer  of  spindle  cells  near  the  ventral  line. 
The  outer  nerve  nest,  or  nerves  amygdalis,  lies  in  the  posterior 
lateral  ventral  part.  It  is  covered  by  a  thin  membranous  layer. 
Its  cells  are  pyramidal  in  shape  and  are  from  10  to  15  millimeters  in 
diameter.  The  cells  terminate  in  spindle  form  toward  the  periphery. 
Nerve  fibers  extend  from  the  anterior  commissure. 

The  outer  wall  of  the  corpus  striatum  consists  of  the  following 
layers: 

An  outer  white  layer  consisting  of  fine  medullated  nerve  fibers 
imbedded  in  a  ground  substance  containing  numerous  nerve  cells. 

A  layer  of  ganglionic  cells,  consisting  of  pyramidal  cells  from  10 
to  15  millimeters  in  diameter,  of  other  round  cells  20  millimeters  in 
diameter,  and  finally  of  cells  only  5  millimeters  in  diameter.  This 
layer  forms  a  reddish  line  in  the  dorsal  portion  of  the  corpus  striatum. 

These  layers  form  part  of  the  median  and  the  posterior  cerebral 
wall  of  the  lateral  ventricle.  The  lateral  ventricle  is  closed  except 
for  a  slit-like  opening  behind  the  posterior  commissure.  This  is  the 
foramen  of  Monro,  through  which  the  lateral  ventricle  communi- 
cates with  the  middle,  or  third,  ventricle. 

The  choroid  plexus  is  found  at  the  base  of  the  lateral  ventricle. 

The  wall  of  the  lateral  ventricle  becomes  thinner  near  the  region 
of  the  transverse  commissure  on  the  surface  toward  the  middle 


NEUROLOGY  297 

brain.  At  this  point  the  pia  mater  and  the  ependyma,  or  the  lining 
cells  of  the  ventricular  membrane,  form  the  major  part  of  the  wall. 

The  domestic  fowl  does  not  have  the  hippocampus. 

The  wall  of  the  middle  ventricle  consists  of  an  outer  white  layer, 
which  is  arranged  similarly  to  that  of  the  corpus  striatum.  The 
ventral  rim  of  the  wall  is  formed  by  a  spiral  band  which  consists 
of  fine  medullated  fibers,  in  which  are  imbedded  a  few  cells. 

The  processus  cerebri  mammillares  are  also  called  the  tubercula 
olfactoria.  From  these  structures  extend  forward  the  olfactory 
nerves,  the  posterior  roots  of  which  may  be  traced  to  the  walls  of 
the  lateral  ventricles. 

The  structure  of  the  processus  cerebri  mammillaris  is  made  up  of 
five  layers  as  follows: 

An  outer  layer,  which  consists  of  colorless  olfactory  fibers  extend- 
ing in  all  directions. 

A  granular  ground  substance  layer,  in  which  are  imbedded  a  few 
cells. 

A  thicker  granular  layer,  on  the  inner  edge  of  which  are  twenty 
large  pyramidal  cells  with  processes  pointing  outward. 

A  layer  of  closely  packed  cells,  in  which  are  fine  medullated  nerve 
fibers.  These  cells  are  about  5  millimeters  in  diameter. 

An  innermost  layer  of  ependymal  cells. 

Near  the  hemisphere  the  peripheral  nerve  fibers  and  nerve  cells 
disappear,  leaving  only  the  ground  substance  of  the  processus  to  aid 
in  the  formation  of  the  hemisphere. 

There  is  a  long  bundle  of  fibers  on  the  lower  surface  of  the  hemi- 
sphere, which  blends  with  the  substance  of  the  olfactory  fibers. 

The  peduncles  of  the  cerebrum  (Fig.  62,  No.  21)  are  the  slightly 
diverging  columns  of  nerve  tissue,  which  form  the  anterior  continua- 
tion of  the  medulla  oblongata  and  disappear  under  the  optic  tracts 
and  the  chiasm. 

THE  SYMPATHETIC  NERVOUS  SYSTEM 

The  sympathetic  nervous  system  commences  anteriorly  at  the 
large  superior  cervical  nerve  ganglion.  This  ganglion,  anteriorly, 
brings  into  communication  the  glosso-pharyngeal,  the  pneumo- 
gastric,  or  vagus,  and  the  sympathetic  system. 

The  following  nerve  trunks  emerge  from  the  superior  cervical 
nerve  ganglion:  a  large  trunk  fusing  with  the  vagus  and  directed 


298  ANATOMY   OF   THE   DOMESTIC    FOWL 

downward,  accompanying  and  surrounding  the  carotid  artery;  a 
second  large  trunk  fusing  with  the  recurrent  pharyngeus  and  the 
glosso-pharyngeus;  a  third  trunk  which  merges  with  the  hypoglossal; 
finally  several  trunks  which  are  distributed  to  the  head. 

The  temporo-lacrimalis,  one  of  the  large  sympathetic  nerves  of 
the  head,  as  it  extends  from  the  cervical  nerve  ganglion,  receives 
branches  from  the  ganglion  radicis  vagi.  This  nerve,  passing  be- 
tween these  two  ganglions,  extends  horizontally  forward  and  out- 
ward through  a  foramen,  crossing  the  glosso-pharyngeus.  Near 
the  Fallopian  canals  it  crosses  the  facial  nerves,  lies  supero-laterally, 
and  receives  a  short  branch  from  the  facial  nerve  whose  fibers  are 
traceable  to  the  geniculate  ganglion.  It  also  receives  a  branch 
from  the  recurrent  maxillaris. 

This  nerve  accompanies  the  external  ophthalmic  artery  forming 
around  it  a  network  of  fibers,  called  the  external  ophthalmic  plexus. 
It  lies  outside  and  downward  from  the  optic  nerve,  sends  fine 
branches  to  the  external  ophthalmic  artery  and  to  the  masseter 
artery,  and  extends  along  with  a  small  branch  of  the  superior 
maxillary  nerve  to  the  skin  of  the  outside  rim  of  the  eye  cavity. 

The  ophthalmic  plexus,  a  second  trunk  extending  to  the  head, 
enters  in  its  course,  anteriorly,  the  lacrimal  plexus.  Its  fibers  also 
supply  the  lacrimal  gland,  and  finally  anastomose  with  the  second 
recurrent  branch  of  the  trigeminus. 

The  sympathetic  caroticus  cephalicus  nerve,  a  third  trunk  extend- 
ing to  the  head,  after  emerging  from  the  large  superior  cervical  nerve 
ganglion,  receives  some  small  branches  from  the  glosso-pharyngeal 
ganglion,  and  then  enters,  in  a  horizontal  manner,  a  foramen,  the 
canalis  caroticus  externus,  located  in  the  lower  part  of  the  basi- 
occipital  and  the  sphenoid  bone.  The  anterior  opening  of  this  fora- 
men, or  canal,  is  close  to  the  posterior  part  of  the  pterygoid  bone. 
Inside  this  canal  the  sympathetic  caroticus  cephalicus  receives  a 
small  branch  'which  extends  in  a  straight  line  from  the  basal  part  of 
the  facial  nerve.  After  receiving  this  branch,  the  nerve  trunk,  pass- 
ing to  the  ear  drum,  lies  close  to  the  petrosum  and  the  sphenoid.  It 
is  covered  by  the  masseter  muscle.  The  carotic  ganglion  is  located 
at  the  point  of  the  fusion  of  the  caroticus  cephalicus  with  the  main 
trunk.  At  this  point  the  caroticus  cephalicus  divides  into  two 
branches.  The  first  is  the  superior  recurrent  nerve,  which  lies 
close  to  the  upper  surface  of  the  alae  of  the  sphenoid,  passes  between 
the  obliquus  externus  and  the  orbital  wall,  around  the  eyeball, 


NEUROLOGY  2  99 

and  finally  into  the  orbital  septum  and  the  internal  muscles  of 
the  eye.  It  communicates  with  the  ophthalmic  nerve  and  sends 
twigs  to  the  lacrimal  gland,  the  gland  of  Harder,  the  upper  eyelid, 
and  the  nose.  The  orbito-nasale  ganglion  is  located  where  these 
nerves  communicate  near  the  nasal  region.  The  second  branch  of 
the  sympathetic  caroticus  cephalicus  is  the  inferior  recurrent  nerve. 
This  branch  passes  forward  and  dorsally  from  the  pterygoid  bone  to 
a  point  where  the  upper  rim  of  the  rising  wings  of  the  jaw  bone  meets 
the  sphenoid  rostrum.  In  this  course,  some  branches  are  given 
off  to  the  pharynx,  one  branch  near  the  lacrimal  gland,  and  a  branch 
which  communicates  with  the  superior  maxillary  nerve  just  before 
the  nerve  enters  the  jaw  bone.  The  spheno-palatine  ganglion  is  at 
the  point  of  fusion. 

The  terminal  branches  of  the  spheno-palatine  are  distributed 
to  the  hard  palate,  the  nose,  and  the  lacrimal  gland. 

From  the  large  cervical  nerve  ganglion  and  near  the  roots  of  the 
caroticus  cephalicus  are  given  off  a  few  small' nerve  fibers  which  pass 
alone  to  the  pharynx  or  accompany  the  jugular  nerve  branches,  and 
fuse  with  the  main  trunk  of  the  caroticus  cephalicus  nerve. 

From  the  large  superior  cervical  nerve  ganglion  the  sympathetic 
trunk,  extends  downward  toward  the  thorax.  It  is  covered  deeply 
with  muscles.  This  portion  is  known  as  the  cervical  sympathetic 
nerve  trunk.  A  trunk  lies  on  each  side  of  the  cervical  vertebrae. 
The  large  thoracic  nerve  ganglion,  the  inferior  cervical,  is  located 
along  this  trunk  at  the  entrance  of  the  thorax.  From  this  ganglion 
there  is  given  off  the  recurrent  cardiacus  which  supplies  the  heart. 
The  end  branches  of  the  sympathetic  nerve  trunk  blend  with  the 
pneumogastric  nerve.  The  inferior  nerve  ganglion  is  the  ganglion 
cardiacum.  Near  this  ganglion  is  found  a  nerve  plexus  in  which 
there  are  imbedded  peripherlistic  ganglia.  This  thoracic  plexus, 
accompanying  the  collica  artery,  passes  to  the  abdominal  region, 
supplying  the  intestines  and  taking  part  in  the  formation  of  the 
abdominal  plexus.  The  abdominal  plexus  is  located  near  the 
anterior  portion  of  the  kidneys.  Its  fibers  are  directed  mainly 
downward  to  the  visceral  organs.  The  large  intestine,  the  rectum 
and  the  copulatory  organs  receive  branches.  These  latter  branches 
take  part  in  the  formation  of  the  pedunda  nerve  plexus.  Some 
branches  of  this  plexus,  follow  the  branches  of  the  posterior  mesen- 
teric  artery. 

The  thoracic  trunk  (Fig.  64,  No.  42)  of  the  sympathetic  is  double. 


300  ANATOMY   OF   THE   DOMESTIC   FOWL 

The  anterior  portion  gives  off  an  anterior  splanchnic  nerve,  or 
plexus  (Fig.  64,  No.  43)  which  accompanies  the  celiac  axial  artery 
to  the  gizzard  and  liver,  communicating  with  the  pneumogastric. 
The  posterior  splanchnic  nerve  is  intimately  combined  with  the 
adrenal  body,  and  the  testes,  or  the  ovary  (Fig.  64,  No.  45).  Intes- 
tinal branches  accompany  those  of  the  mesenteric  arteries  (Fig.  64, 
No.  46).  Other  branches  supply  the  kidneys,  and  communicate 
with  long  branches  of  the  spinal  nerves  destined  for  the  cloaca  and 
adjacent  parts,  and  thus  form  a  plexus  similar  to  that  found  in 
mammals. 

FUNCTIONS  OF  THE  NERVOUS  SYSTEM 

According  to  function,  the  nerves  composing  the  trunks  are 
divided  into  afferent  and  efferent. 

The  afferent  nerves  are  those  that  convey  the  impulses  from  the 
periphery  of  the  body  to  the  nerve  center,  which  are  located  in  the 
brain  or  in  the  spinal  cord.  The  impulses  conveyed  are  those  of 
special  senses,  as  sight,  hearing,  taste,  touch,  and  smell.  Impulses 
producing  sensation  pleasurable  or  painful  come  from  the  skin,  the 
muscle,  or  the  viscera. 

The  efferent  nerves  are  those  which  convey  impulses  from  the 
nerve  centers  to  the  periphery.  These  impulses  may  be  motor  as 
those  going  to  the  muscle  cells  of  the  skeletal  muscles,  the  viscera, 
or  the  blood-vessels.  These  motor  impulses  make  movements  in 
these  organs  possible.  In  the  blood-vessel  they  result  in  the  control 
of  the  caliber  of  the  vessel.  These  impulses  may  be  of  an  inhibitory 
character,  as  in  slowing  the  heart.  They  may  be  secretory  impulses 
stimulating  the  gland  to  activity  or  regulating  metabolism. 

The  ganglia  are  nerve  centers  which  receive  and  generate  im- 
pulses; the  nerve  trunks  are  filaments  which  convey  impulses.  The 
gray  matter  of  the  cord  described  above  is  the  ganglionic  portion, 
and  the  outer  white  matter  is  made  up  of  nerve  fibers  which  convey 
impulses  from  one  part  of  the  cord  to  another,  or  to  and  from  the 
brain. 

The  nerves  that  have  their  roots  in  the  spinal  cord  superiorly, 
are  sensory;  that  is,  they  convey  the  sensory  impulses  from  the 
periphery  to  the  cord  ganglion  and  to  the  brain.  They  have  a 
ganglion  just  outside  the  cord. 

The  nerves  that  have  their  roots  in  the  spinal  cord  inferiorly; 
that  is,  they  convey  motor  impulses  from  the  nerve  centers  to  the 


NEUROLOGY  301 

periphery.  The  function  of  the  inferior  roots  is  to  supply  all  the 
voluntary  muscles  as  well  as  the  oviduct,  the  intestines,  and  other 
hollow  viscera,  including  the  blood-vessels  with  the  power  of  move- 
ment. Many  of  these  fibers  pass  to  the  sympathetic  ganglion  and 
are  distributed  as  sympathetic  nerve  fibers. 

The  cord  is  divided  into  different  tracts,  that  is,  certain  groups 
of  fibers  convey  certain  kinds  of  impulses. 

The  superior  column  of  the  cord  conveys  to  the  cerebrum  such 
impressions  as  temperature,  pressure,  and  muscular  tension. 

The  fibers  of  the  lateral  columns  carry  sensations  of  pain. 

The  fibers  of  the  direct  cerebellar  tract  carry  impulses  which 
result  in  the  maintenance  of  the  equilibrium  of  the  body. 

All  the  voluntary  impulses  originate  in  the  cerebrum,  pass  through 
the  cerebellum  and  travel  direct  to  the  bulb;  they  then  pass  over 
to  the  opposite  side,  and  travel  by  the  crossed  pyramidal  tract  to 
the  multipolar  cells  of  the  inferior  horn  of  the  spinal  cord,  and  trans- 
mit the  impulse  through  motor  fibers  that  originate  at  that  point  in 
the  cord. 

All  sensory  impulses  enter  the  brain  on  the  side  opposite  their 
origin,  and  all  motor  impulses  leave  the  brain  on  the  side  opposite 
that  to  which  they  are  distributed.  Injury  of  the  motor  area  of  the 
right  side  of  the  brain  leads  to  paralysis  of  the  left  side  of  the  body. 

An  impulse  of  the  vasomotor  nerve  travels  in  the  lateral  column 
of  the  cord. 

A  nerve  impulse  may  originate  in  the  brain  and  be  modified  in 
passing  through  a  ganglion  in  the  spinal  cord  or  in  the  sympathetic 
system. 

The  system  of  reflex  action  is  as  follows:  first,  an  efferent  nerve 
which  conveys  the  impulse  from  the  periphery  to  a  nerve  center; 
second,  a  ganglion,  or  nerve  center,  to  receive  the  impulse  and  gen- 
erate other  impulses;  third,  an  efferent  nerve  to  convey  the  impulse 
from  the  nerve  center  to  the  periphery. 

The  following  is  an  example  of  reflex  action.  The  foot  of  a  fowl 
is  pierced  with  a  pin.  The  sensory  impulse  is  conveyed  by  sensory 
nerve  fibers  to  the  nerve  centers.  In  this  center  the  ganglionic 
nerve  cells  generate  a  motor  impulse  which  is  sent  back  through  the 
motor  nerve  fiber  to  the  muscles  controlling  the  part.  The  result 
is  that  the  muscle  contracts  and  jerks  the  foot. 

There  are  many  functional  centers  located  in  the  medulla  oblon- 
gata.  Destruction  of  this  part  of  the  system  results  in  instant  death 


302  ANATOMY    OF   THE   DOMESTIC  FOWL 

of  the  bird.  In  addition  to  furnishing  a  path  for  fibers  carrying 
impulses  from  the  body  to  the  cerebrum,  it  furnishes  a  large  number 
of  centers  for  such  functions  as  respiration,  swallowing,  secretion, 
temperature,  and  vasomotor  and  cardiac  activity. 

The  function  of  the  cerebellum  is  principally  that  of  coordination. 
It  brings  about  harmony  and  rhythm  in  muscular  movements.  If 
the  cerebellum  be  removed,  the  bird  can  no  longer  walk.  It  has 
lost,  with  this  removal,  all  power  to  coordinate. 

The  cerebrum  of  the  bird  has  no  convolutions,  and  the  gray,  or 
ganglionic,  portion  is  thin,  indicating  low  power  of  intelligence. 
There  are  certain  areas  presiding  over  other  functions,  as  motor 
areas,  sensory  areas,  and  so  on. 

A  careful  study  of  the  brain  of  the  fowl  shows  us  that  the  centers 
presiding  over  sight  and  smell  are  well  developed. 

The  olfactory  bulbs  are  the  centers  of  the  sense  of  smell. 

The  optic  thalamus  is  the  center  of  the  sense  of  sight. 

The  sympathetic  nerve  system  transmits  impulses  to  the  invol- 
untary muscular  structure  of  all  organs,  including  those  of  the 
intestinal  tract,  the  blood-vessels,  and  perhaps  also  the  glands. 


ESTHESIOLOGY 

THE  SENSE  ORGANS 

The  five  special  senses  are  seeing,  smelling,  tasting,  hearing,  and 
feeling. 

THE  ORGAN  OF  SIGHT 

The  sense  of  sight  in  the  bird  is  well  developed.  The  eye  (Fig.  26; 
D,  E  and  F),  the  organ  of  sight,  is  relatively  large,  round  laterally, 
and  rather  flattened  antero-posteriorly.  It  is  located  at  the  side  of 
the  head.  The  eyeball  is  only  slightly  movable.  The  septum 
interorbital  separates  the  two  eyeballs  laterally.  As  in  mammals, 
the  eyeball  has  three  coats,  which  are  from  inside  to  outside,  the 
retina,  the  choroid,  and  the  sclera.  The  sclerotic  coat  is  completed 
anteriorly  by  the  cornea  with  which  it  forms  a  union  called  the 
corneo-sderal  juncture.  Around  the  cornea  the  sclerotic  coat  con- 
tains a  ring  of  osseous  scales  varying  in  number  from  twelve  to 
twenty.  The  sclera  may  become  ossified  posteriorly,  forming  an 
osseous  sheath  around  the  optic  nerve.  The  pecten  is  a  vascular 
comb-like  membrane  stretching  from  the  nervous  opticus  to  the 
crystalline  lens.  The  choroid  coat  is  always  black.  The  pupil  in 
the  hen  is  also  black  and  round.  The  iris  contains  striated  muscular 
fibers.  The  membrana  nictitans,  located  at  the  inner  angle  is  well 
developed.  It  is  moved  by  two  muscles  (Fig.  26,  No.  B,  7,  8,  10). 
The  lacrimal  gland  and  the  gland  of  Harder  are  present.  There  is 
no  mebomian  gland. 

The  tears  are  secreted  by  the  lacrimal  gland  and  are  drained  away 
from  the  fore  part  of  the  eyeball  by  two  small  canals  which  extend 
into  a  lacrimal  sac.  From  this  sac  there  extends  a  tube  into  the 
nasal  cavity  called  the  lacrimal  duct. 

The  lower  lid  is  the  larger  and  often  incloses  a  small  cartilaginous 
plate.  The  conjunctiva  is  a  true  mucous  membrane  which  covers 
the  anterior  portion  of  the  eye  cavity  attaching  to  the  cornea- 
scleral  juncture. 

The  choroidea  is  rich  in  pigment.  On  its  inner  surface  lies  the 
dark  pigment  layer  of  the  retina.  The  corpus  ciliare,  that  part  of 

303 


304  ANATOMY    OF    THE   DOMESTIC   FOWL 

the  choroid  coat  bearing  the  ciliary  processes,  consist  of  numerous 
folds.  The  ciliary  muscles  are  arranged  obliquely.  Each  consists 
of  three  digitations. 

The  iris  is  covered  on  the  posterior  side  with  pigment,  the  color 
of  which  determines  the  color  of  the  eye.  The  yellow  pigment  of 
the  iris  has  been  said  to  be  due  to  carotin  and  zanthophyll  and  the 
black  pigment  to  melanin.  The  enlarging  and  the  contracting  of 
the  pupil  is  brought  about  by  muscles.  The  reduction  of  the 
pupillary  caliber  is  due  to  the  sphincter  pupillary  muscle.  It  is 
said  by  some  anatomists  that  the  muscles  controlling  the  caliber  of 
the  pupil  in  the  bird  furnish  voluntary  motion  and  that  the  capability 
of  accommodation  of  the  eyes  is  greater  in  birds  than  in  mammals. 

The  retina  contains  no  blood-vessels;  otherwise  the  structure  is 
similar  to  that  of  mammals.  The  crystalline  lens  is  flattened  on  the 
corneal  side  and  is  convex  posteriorly.  The  lens  epithelium  de- 
velops into  fibers  in  the  parts  close  to  the  equator,  and  are  almost 
perpendicular  to  the  eye  axis.  The  corneal  portion  is  relatively 
small. 

The  sclerotic  coat  is  dense  and  white.  It  is  divided  into  three 
layers.  It  is  thin  and  flexible,  and  somewhat  elastic  posteriorly. 
It  has  an  internal  layer  of  hyaline  cartilage.  Anteriorly  its  form 
is  maintained  by  the  circle  of  osseous  plates  mentioned  above. 
These  plates,  interposed  between  the  exterior  and  the  middle  layer, 
are  located  immediately  behind  the  cornea.  The  scales  are  thin 
and  of  oblong  quadrate  shape,  being  elongated  from  before 
backward. 

The  choroid  coat  is  a  membrane  loosely  cellular  and  highly 
vascular.  It  is  impregnated  by  a  black  pigment.  Opposite  the 
bony  circle  the  choroid  separates  into  two  layers.  The  external 
layer  is  the  thinner  and  adheres  at  first  firmly  to  the  sclerotic;  it 
passes  forward  to  become  continuous  with  the  iris.  The  inner  layer 
is  thicker  than  the  external.  The  two  layers  are  made  up  of  radiat- 
ing fibers  which  terminate  anteriorly  in  the  ciliary  processes,  the 
ends  of  which  are  adherent  to  the  capsule  of  the  crystalline  lens. 

The  iris  is  delicate  in  structure.  It  is  composed  of  a  fine  network 
of  interlacing  fibers. 

The  ciliary  nerves  and  blood-vessels,  run  in  the  form  of  single 
trunks  between  the  choroid  and  the  sclerotic,  and  terminate  ante- 
riorly in  a  ring-shaped  plexus  for  the  supply  of  the  iris  and  the 
muscular  circle  of  the  cornea.  As  stated  before,  the  pupil  in  the 


ESTHESIOLOGY  305 

fowl  is  round,  but  in  the  goose  it  is  elongate  transversely;  and  in 
the  owl,  a  vertical  oval. 

The  optic  nerve  approaching  the  sclerotic  coat  becomes  altereH 
into  a  conical  extremity,  which  enters  a  sheath  and  is  directed  down- 
ward and  obliquely  forward.  The  extremity  of  the  optic  nerve  in 
the  interior  of  the  eye  presents  a  white  narrow  streak.  Branches  of 
the  opthalmic  artery  enter  the  eye  between  the  lamina  of  the  retina, 
along  the  whole  extent  of  the  oblique  slit,  and  penetrate  the  fold  of 
the  pecten  upon  which  they  form  a  delicate  ramification. 

The  crystalline  lens  is  of  soft  texture.  It  is  inclosed  in  a  capsule 
and  is  nearly  round.  It  adheres  very  firmly  in  the  depression  in  the 
anterior  part  of  the  vitreous  humor.  The  capsule  is  lodged  between 
two  layers  of  hyaloidea,  which  as  they  recede  from  each  other,  leave 
around  its  circumference  the  sacculated  canal  of  Petit. 

The  cornea  is  of  horny  consistency  and  is  transparent.  Light 
thus  rapidly  passes  through  it  to  the  posterior  part  of  the  eye. 

The  vitreous  chamber,  lying  back  of  the  crystalline  lens,  contains 
a  clear  jelly-like  substance. 

THE  ORGAN  OF  HEARING 

The  ear,  the  organ  of  hearing,  has  in  the  fowl  no  conchal  cartilage. 
The  external  auditory  meatus,  or  canal  opening,  is  found  on  each 
side  of  the  head,  and  is  usually  guarded  by  a  few  stiff,  short  feathers. 
In  some  kinds  of  birds  these  feathers  are  capable  of  being  erected 
so  as  to  direct  the  waves  of  sound  into  the  inner  ear.  The  outer 
entrance  of  the  ear  contains  glands.  This  canal  is  short.  It  leads 
to  the  drum,  which  is  somewhat  convex  from  the  outside,  and  which 
has  a  membrane  forming  a  complete  curtain  stretched  over  the 
outer  part.  The  irregularly  formed  drum  has  connection  with  the 
air-containing  cavity  of  the  skull,  and  by  a  thin  cartilaginous  canal, 
the  Eustachian  tube,  with  the  pharynx.  The  auditory  ossicles  are 
represented  by  only  a  single  bone,  called  the  columella,  which 
most  closely  represents  the  stapes  of  mammals.  This  is  attached 
by  processes  of  cartilage  to  the  tympanic  membrane.  Owen  con- 
siders these  cartilages  as  representing  the  malleus  of  mammals. 
Huxley  on  the  other  hand  considers  them  to  represent  the  incus. 
Originating  from  the  processes  is  a  small  muscle  which  is  attached 
to  the  drum.  This  is  by  Shufeldt  considered  the  Tensor  tympani. 
The  drum  cavity  through  the  fenestra  vestibularis  and  cochlearis 
is  connected  with  the  labyrinth. 
20 


306  ANATOMY   OF   THE    DOMESTIC  POWL 

The  inner  ear  consists  of  a  membranous  labyrinth,  surrounded  by 
a  spongy  bony  structure — the  bony  labyrinth.  In  it  are  recognized 
the  vestibulum,  the  three  half-circle  shaped  canals,  and  the  cochlea. 
The  superior  semicircular  canal  is  the  largest.  The  acoustic  nerve 
enters  at  the  end  of  the  canals  near  the  ampullae.  The  nerves  are 
supported  in  delicate  vascular  membranes  lining  the  canals  and 
slightly  projecting  into  the  ampullae. 

The  vestibulum  is  a  small  irregular  cavity  which  communicates 
with  the  arcades  and  the  cochlea,  and  through  the  fenestra  vesti- 
bularis  with  the  drum  cavity.  The  endolymph  of  the  vestibulum 
contains  microscopic  crystals  of  calcium  carbonate.  The  semi- 


FlG.  78. — Diagram  of  the  inner  ear.  I,  The  integument.  2,  The  superior 
semicircular  canal.  3,  The  external  canal.  4,  The  horizontal  canal.  5,  The 
ampulla.  6,  The  obtuse  osseous  conical  cochlear  cavity.  7,  The  Eustachian 
tube.  8,  The  tympanum.  9,  Filaments  of  the  auditory  nerve. 

circular  canals  are  relatively  larger  and  thicker  than  in  mammals. 
The  ampullae  in  the  upper  and  back  part  are  separated  by  walls. 
The  cochlea  is  an  obtuse  conical  tube-like  structure  slightly  curved 
at  the  blind  extremity  with  the  concavity  directed  backward.  It 
contains  a  membranous  lining.  At  this  point  the  cochlea  is  broad- 
ened and  accommodates  a  branch  of  the  auditory  nerve.  This 
nerve  spreads  out  in  fine  filaments  upon  the  surface  of  the  tubes. 
The  hollow  space  of  the  cochlea  is  divided  by  a  spiral  partition, 
making  two  chambers,  the  scala  vestibuli  and  the  scala  tympani. 
These  walls  extend  from  the  beginning  of  the  cochlea. 

The  tympanic  cavity  is  formed  by  the  occipital,  the  basi-  and  ali- 
sphenoids,  the  petrosal  portion  of  the  temporal  bone.  It  represents 
the  stapedial  canal  leading  to  the  foramen  ovalis  and  the  pneumatic 


ESTHESIOLOGY  307 

apertures  by  which  the  air  from  the  Eustachian  tube  is  conducted  to 
the  precranial  diploae. 

THE  ORGAN  OF  SMELL 

The  nose  is  the  seat  of  the  peripheral  portion  of  the  organ  of  the 
sense  of  smell.  The  terminals  of  the  olfactory  nerves,  which  receive 
the  impressions  of  odors,  are  broadened  in  the  mucous  membrane  of 
the  walls  of  the  anterior  nares.  There  are  no  ethmoidal  volutes,  or 
sieve-like  structure,  in  birds.  The  nerve  extends  from  the  anterior 
portion  of  the  brain  in  cone-shape,  finally  dividing  into  filaments 
which  are  distributed  over  the  mucous  surface  of  the  turbinated 
bones. 

THE  ORGAN  OF  TASTE 

The  most  important  part  of  the  organ  of  taste  is  the  tongue. 
In  birds  the  dorsum  of  the  tongue  is  covered  by  a  thick  stratum 
corneum,  a  heavy  layer  of  stratified  squamous  epithelium.  The 
tongue,  therefore  is  not  in  birds  so  well  adapted  for  the  perception 
of  taste  as  it  is  in  mammals.  The  lingual  branch  of  the  trigemini 
is  lacking  in  birds.  This  fact  makes  the  ninth  pair,  or  the  nervi 
glosso-pharyngei,  the  exclusive  nerves  of  taste.  There  is  an  opinion 
ventured  by  one  anatomist  that,  since  the  first  and  the  second  branch 
of  the  fifth  pair,  or  trigemini,  have  terminal  filaments  in  the  hard 
palate,  they  may  furnish  fibers  for  the  sense  of  taste.  There  are 
many  taste  cells  on  the  tongue  and  on  the  dorsal  palate. 

THE  ORGAN  OF  TOUCH 

The  peripheral  parts  of  the  organ  of  touch  in  the  fowl  are  the  skin 
and  the  feathers. 

In  a  few  birds  special  touch  and  taste  perception  can  be  supplied 
by  the  edge  and  point  of  the  beak. 

In  the  skin  of  birds  are  found  numerous  sensory  nerve  endings  for 
tactile  sense. 

The  sensory  nerves,  which  provide  the  sense  of  touch,  usually 
terminate  in  one  of  two  forms.  The  first  are  the  Herbst's  bodies, 
which  in  many  respects  are  similar  to  the  Picinian  bodies. 

Herbst's  touch  corpuscles  are  found  on  all  parts  of  the  skin;  they 
are  especially  numerous  in  the  region  of  the  tail  and  of  the  wing.  In 
the  wing  they  are  particularly  numerous  in  the  region  of  the  flight 


308  ANATOMY   OF    THE   DOMESTIC    FOWL 

feathers.  They  occur  in  large  numbers  in  the  periosteum  of  the 
anterior  tibial  region  and  in  the  mucous  membrane  of  the  cloaca  and 
of  the  generative  organs.  They  are  numerous  in  the  conjunctiva 
and  on  the  surface  of  the  tongue.  They  are  also  found  in  the  gums 
and  in  the  beak. 

Herbst's  corpuscle  is  made  up  of  a  central  fiber-shaped  part  with 
a  smooth  extension  of  the  axis  cylinder  of  its  nerve  (Fig.  29,  (7). 
This  central  fiber  is  surrounded  by  a  peculiar  protoplasmic  body. 
Outside  of  this  there  is  a  double  row  of  cubical  cells  which  surround 
the  axial  part.  These  are  close  together.  Outside  of  these  there 
occurs  a  concentric  lamellar  layer,  which  contains  cells.  In  the 
periphery  these  lamellae  become  more  distinct  and  contain  larger 
but  fewer  cells.  The  capsule  is  made  up  of  very  thin  layers,  which 
are  continued  into  the  perineural  layer.  Each  body  contains  a 
thin  outer  zone.  The  nerve  fiber  passes  in  a  regular  manner  from 
the  axis  cylinder,  the  myelemma,  and  the  sheath  of  Schwann,  and 
as  a  delicate  nerve  twig  is  surrounded  by  a  sheath  consisting  of 
several  perineural  layers.  As  it  enters  the  center  of  the  touch  cor- 
puscle, it  loses  its  myeline  sheath  near  the  base  of  the  body,  and  the 
terminal  fiber  becomes  flattened.  Its  rim  is  directed  toward  the 
two  rows  of  cubical  cells,  and  it  ends  in  a  rounded  knob. 

The  touch  corpuscles  are  the  largest  in  the  mucous  membrane  of 
the  cloaca  and  smallest  in  the  skin.  Hess  has  found  these  touch 
corpuscles  in  the  large  filiform  papillae  on  the  side  of  the  tongue 
and  a  few  on  its  lower  surface.  They  are  also  found  in  the  soft  skin 
of  the  edges  and  inner  borders  of  the  beak. 


STRUCTURE  OF  APPENDAGES 

The  skin  of  the  fowl  is  very  thin  and  does  not  contain  oil  glands  or 
sweat  glands.  In  the  fowl  the  oil  is  supplied  by  a  tail  or  rump  gland, 
the  glandula  uropygii  (Fig.  35,  No.  16).  This  gland  is  round  or  oval 
in  shape,  and  about  the  size  of  a  pea  and  consists  of  two  lobes.  It 
is  of  the  tubular  variety  with  a  teat,  which,  in  most  instances  has  two 
openings.  A  medium  septum  divides  the  gland  into  two  halves. 
The  oil  secreted  by  the  columnar  epithelial  cells  is  collected  in  a 
body  cavity  located  in  the  center  of  the  gland;  this  has  a  duct  extend- 
ing to  the  surface.  The  bird  by  squeezing  out  a  quantity  of  this 
oil  into  its  beak  oils  the  feathers,  passing  the  beak  over  them,  one 
by  one.  The  oil  renders  the  feathers  practically  impervious  to 
water.  It  is  necessary  for  the  bird  to  give  proper  attention  to  its 
plumage  in  order  that  the  feathers  appear  in  prime  condition.  Should 
there  be  a  disease  of  the  oil  gland,  or  should  the  bird  become  ill  and 
neglect  its  toilet  the  result  is  an  unkempt  appearance  of  the  plumage, 
the  feathers  becoming  rather  rough  and  more  or  less  injured  by  the 
weather. 

The  subcutis  is  well  developed  and  furnishes  to  the  cutis  great 
capability  for  movement,  which  is  necessary  for  the  rising  and  fall- 
ing of  the  feathers.  The  corneum  is  very  thin.  Papillary  bodies 
are  present  only  in  a  very  few  places,  such  as  the  region  about  the 
eye  and  on  the  toes.  Where  the  toes  touch  the  ground  in  walking 
there  are  large  wart-like  thickenings  of  the  epithelium.  In  most 
birds  the  shanks  are  unfeathered.  The  epidermis  on  the  feathered 
parts  of  the  skin  is  thin,  dry  on  the  surface,  and  abounds  in  continu- 
ous scales.  The  stratum  corneum  is  very  thick  on  the  horny  sheath 
of  the  beak,  on  the  top  of  the  toes,  on  the  spurs  of  the  cock,  and 
on  the  scale  plates  that  cover  the  skin  on  the  shanks.  The  feathers 
of  birds  serve  the  same  protective  purpose  as  hair  on  mammals. 
In  cold  weather  the  skin  muscles  controlling  the  feather  movements 
contract;  thus  the  feathers  become  ruffled  much  as  we  observe  the 
hair  standing  erect  on  horses  under  similar  conditions.  By  increas- 
ing the  dead  air  space  around  the  body,  the  radiation  of  heat  is  re- 
tarded, and  the  body  kept  warmer.  The  corneum  of  the  skin  is  not 

309 


310  ANATOMY   OF   THE   DOMESTIC   FOWL 

usually  rich  in  blood-vessels;  however,  in  the  domestic  fowls  there 
is  in  the  comb,  in  the  wattles,  and  similar  appendages  of  the  head,  a 
thick  vascular  network. 

The  beak  and  the  claws  are  modified  skin;  they  are  true  horn  mate- 
rial. At  the  base  of  the  beak  there  is  often  formed  scales,  which 
surround  the  nostrils,  in  whole  or  in  part,  and  have  a  naked,  or 
waxy,  appearance,  which  is  known  as  the  cera. 


FIG.  79. — Photomicrograph  of  the  section  of  skin  from  the  sole  of  the  foot  of 
a  hen.  i,  Horny  stratified  squamous  epithelium,  a,  Stratum  corneum.  b, 
Stratum  lucidum.  c,  Stratum  germinativum.  2,  Connective  tissue  supporting 
membrane,  pars  reticularis.  3,  Blood-vessels. 

The  feathers  may  be  considered  of  two  chief  kinds,  the  quill 
feathers  and  the  clothing  feathers.  The  most  rudimentary  of  the 
latter  are  known  as  down.  A  quill  feather  consists  of  two  principal 
parts:  the  quill,  or  calamus,  and  the  vane,  or  vexillum.  The  quill 
is  continuous  with  the  central  shaft,  called  the  rachis,  the  two  form- 
ing the  stem  of  the  feather.  Projecting  outward  from  the  stem  on 
each  side  are  a  large  number  of  pointed  and  very  flexible  barbs. 
These  barbs  are  located  nearly  at  right  angles  to  the  quill  and  have 
extending  from  them  at  right  angles  smaller  processes  or  barbules. 


STRUCTURE  OF  APPENDAGES  311 

These  barbules  hook  together  the  barbs  and  give  the  web  its  form. 
In  some  feathers,  as  the  hackle,  and  in  the  wing  bar  feathers  of  the 
male  of  some  breeds,  there  is  a  portion  of  the  upper  outer  edge  of  the 
feather  not  provided  with  barbules,  "which  fact  gives  the  feather  its 
characteristic  appearance.  The  down  feathers  are  loose  and  fluffy. 
In  this  kind  of  feather  the  shaft  is  weak,  and  the  barbs  are  not 
provided  with  barbules.  The  barbs  like  the  shaft  may  be  considered 
weak.  These  feathers  give  great  warmth  to  the  body.  There  are 
fiber  feathers  appearing  as  hair-like  filaments,  and  called  filo-pluma. 
These  are  found  scattered  over  the  body;  they  are  particularly  abun- 
dant in  the  region  of  the  head  and  the  neck. 

At  each  end  of  the  quill  is  a  small  opening,  or  umbilicus.  Inside 
the  barrel  of  the  feather  there  is  pulp,  which  in  young  feathers  is 
very  vascular;  the  vessels  entering  by  the  proximal  umbilicus  are 
buried,  along  with  part  of  the  quill,  in  a  papillated  follicle  of  the 
skin.  From  this  follicle  the  feather  is  developed.  At  the  base  of 
the  shaft  a  secondary  rudimentary  quill  is  usually  formed,  which 
may  be  represented  by  a  mere  tuft  of  down.  On  the  same  general 
principle  the  smaller  feathers  are  constructed.  These  cover  the 
body,  the  upper  parts  of  the  legs,  and  the  head,  while  the  larger 
feathers  and  quills  are  confined  to  the  wings  and  the  tail.  The 
longest  quill  feathers  are  those  arising  from  the  hand,  called  the 
primaries.  Those  arising  from  the  forearm  are  called  the  second- 
aries. Those  that  are  developed  from  the  proximal  part  of  the  arm 
are  called  the  tertiaries.  The  rudimentary  pollux  carries  some  feath- 
ers which  form  the  alula,  or  bastard  wing.  The  scapularies  are 
feathers  covering  the  scapula  and  the  humerus.  Covering  the 
bases  of  the  larger  flight  feathers  are  wing  coverts  consisting  of 
several  rows  of  small  feathers.  The  quill  feathers  of  the  tail  are 
called  the  rectrices.  The  rectrices  have  considerable  mobility;  their 
bases  are  covered  by  a  row  of  tail  coverts. 

The  pedal  digits  of  the  natatores  are  joined  by  a  membrane, 
covered  with  scaly  skin,  which  forms  the  web  foot. 

The  feathers  in  many  parts  of  the  body  are  developed  in  rows, 
there  being  intervals,  or  elongated  skin  areas,  between  these  groups 
of  several  rows,  which  are  not  provided  with  feather  papillae,  but 
which  are  covered  over  by  the  feathers  developed  in  front  of  these 
spaces.  The  definite  feather  lines,  or  areas,  have  been  called 
pteryla.  The  intervening  tracts  devoid  of  feathers  are  called  the 
apteria. 


3I2 


ANATOMY   OF    THE   DOMESTIC   FOWL 


The  first  outer  covering  of  the  bird,  or  baby  chick,  is  a  temporary 
one  consisting  of  fasciculi  of  long  filaments  of  down.  These 
fasciculi  on  their  first  appearance,  are  enveloped  in  a  sheath,  which 
soon  becomes  ruptured  and  are  entirely  cast  off  by  the  time  the 
baby  chicks  are  ready  to  be  taken  from  the  nest  or  the  incubator. 


FIG.  80. — Photomicrograph  of  the  skin  of  the  neck  of  a  S.  C.  White  Leghorn 
hen.  i,  The  skin  possessing  an  outer  stratum,  the  stratum  corneum,  next  the 
stratum  lucidum,  next  the  stratum  granulosum  and  underneath  the  stratum 
germinativum.  Beneath  the  outer  dark  band  representing  the  upper  skin 
strata  is  the  pars  reticularis  of  the  derma.  2,  Papilla  showing  from  inside  to 
outside  the  hyaline  feather  wall,  the  stratum  corneum,  the  Malpighian  layer  of 
the  follicle,  the  corium.  Inside  the  feather  is  noted  the  pulp-like  material. 

The  down  fasciculi,  each  emerging  from  its  small  quill,  are 
succeeded  by  the  feathers,  which  they  apparently  guide  through  the 
skin. 

Feathers  do  not  spring  from  all  parts  of  the  body  alike;  especially 
devoid  of  feathers  are  those  parts  where  chafing  and  friction  is 
greatest,  as  under  the  wings  and  in  the  groin. 

At  the  end  of  the  quill  there  is  a  small  opening,  the  inferior 
umbilicus,  into  which  projects  a  papilla  of  the  dermis.  Where  the 


STRUCTURE  OF  APPENDAGES  313 

quill  emerges  from  the  skin  there  is  another  small  opening,  the 
superior  umbilicus,  from  which  springs  frequently  a  small  feather 
called  the  hyporachis.  The  shaft,  or  rachis,  has  a  groove  extending 
along  that  surface  which  lies  next  the  body. 

In  the  newly  formed  chick  the  first  indication  of  feathers  is  the 
formation  of  papillae,  which  is  constituted  by  The  upward  growth  of 
the  dermis,  or  the  sensitive  and  vascular  parts  of  the  skin.  Then 
the  skin  immediately  around  the  papilla  sinks  downward,  so  that 
later  the  papilla  is  inclosed  in  a  follicle  of  the  skin.  The  epidermis 
over  the  papilla  is  the  same  as  over  the  rest  of  the  surface.  The 
horny  outer  layer  of  the  epidermis  forms  for  the  growing  feather  a 
protective  sheath  which  is  cast  off  as  the  feather  is  formed.  The 
feather  proper  develops  from  the  underlying  germinative  layer, 
which  as  the  feather  develops,  forms  a  cylinder  of  cells.  The  lower 
part  of  the  cylinder  is  in  touch  with  the  papilla;  this  later  becomes 
the  quill  (Fig.  80,  No.  2).  The  upper  part  of  the  cylinder  develops 
the  web  portion  of  the  feather.  As  soon  as  the  feather  is  fully 
developed  the  papilla,  which  has  projected  into  the  quill  and 
nourished  it,  is  withdrawn,  and  the  quill  becomes  filled  with  a  pith- 
like  material  forming  septa,  which  extend  in  different  directions. 

Once  a  year,  usually  in  the  late  summer  or  in  the  fall,  the  entire 
feather  coat  is  changed.  This  process  is  called  molting.  During 
this  time  the  bird  appears  in  a  somewhat  depressed  condition,  the 
hen  almost  always  ceases  laying.  Birds  also  molt  in  the  spring, 
to  a  limited  extent.  The  male  at  this  time  takes  on  the  so-called 
breeding  plumage,  which  is  the  most  beautiful  of  the  year.  It  has 
recently  been  established  by  Rice,  that  the  young  fowl,  in  reaching 
a  stage  of  egg  production,  molts  five  times  before  the  laying  period 
begins. 

The  structure  of  the  skin  of  fowls  is  similar  to  that  of  the  skin  of 
mammals.  The  skin  consists  of  two  layers  the  outer  portion,  or 
epidermis,  and  the  inner  true  skin,  the  cutis,  corium,  or  dermis.  If 
we  study  a  section  of  skin  from  the  shank  region  of  a  fowl  we  find 
the  outer  portion  is  differentiated  into  two  distinct  regions,  the  rete 
Malpighii  and  the  stratum  corneum.  The  stratum  corneum  is  the 
outer  horny  layer.  The  cells  making  up  this  portion  are  fusiform, 
flattened,  and  in  regular  rows.  The  nuclei  in  these  layers  of  cells 
are  not  pronouncedly  visible,  and  the  outline  of  the  cells  not  clear 
in  a  section  such  as  used  in  our  ordinary  methods  of  study.  The 
corneum  is  a  compact  mass  of  remnant  cells  which  have  lost  the 


314  ANATOMY   OF   THE  DOMESTIC  FOWL 

appearance   and    their   texture   of   living   cells.     It   thus  becomes 
modified  into  scales  upon  the  skin  surface. 

Between  the  stratum  corneum  and  the  stratum  Malpighii  there 
is  another  zone  which  consists  of  the  cells  undergoing  a  transitional 
stage  from  a  cubical  shape  to  a  more  flattened  appearance,  and 
gradually  becoming  more  granular  and  hyaline. 

The  various  parts  of  the  epidermis  are  in  close  genetic  relation- 
ship to  one  another.  The  upper  layer  of  epithelium  is  constantly 
being  desquamated.  This  casting  off  is  compensated  for  by  a 
continuous  upward  pushing  of  its  lower  elements.  Cell  prolifera- 
tion occurs  in  the  basal  cells  and  in  adjacent  cellular  strata  of  the 
stratum  germinativum,  or  stratum  Malpighii,  where  the  elements 
are  often  seen  in  process  of  mitosis,  or  cell  division.  The  young  cells 
are  gradually  pushed  upward.  During  their  course  they  assume  the 
general  characteristics  of  the  elements  composing  the  layers  through 
which  they  pass.  This  process  is  as  follows:  each  cell  changes  first 
into  a  cell  of  the  stratum  Malpighii;  then,  when  it  commences  the 
formation  of  keratohyalin,  it  changes  into  a  cell  of  the  stratum 
granulosum;  later  still,  into  a  cell  of  the  stratum  lucidum;  and  finally 
into  an  element  of  the  stratum  corneum,  where  it  gradually  loses 
its  nucleus,  cornifies,  and  at  last  drops  off. 

The  mesodermic  portion  of  the  skin  consists  of  loose,  subcutaneous 
connective  tissue  containing  some  fat.  The  amount  of  adipose  tissue 
in  the  subcutaneous  layer  is  subject  to  great  variation;  there  are  a 
few  places  in  which  there  is  little  or  no  fat.  The  upper  portion 
of  this  layer  contains  a  few  elastic  fibers,  which  interlace  and  run 
in  all  directions.  Numerous  round  or  oval  cells  are  found  in  the 
upper  region.  The  lower  and  middle  portions  of  the  corium  are 
richly  supplied  with  blood-vessels  terminating  into  capillaries,  which 
penetrate  the  portions  bordering  the  epidermis.  Nerves  giving  off 
terminal  branches  also  occur. 

The  various  colors  of  the  skins  of  fowls  are  due  to  the  distribution 
of  various  quantities  of  two  colors,  orange-yellow  and  brownish-black. 

The  yellow  pigment  is  probably  carotin  and  xanthophyll,  two 
pigments  contained  in  association  with  the  chlorophyll  of  plants, 
which  the  bird  obtains  in  its  feed.  These  coloring  matters  were 
formerly  called  lipochrome;  but  as  lipochrome  may  be  any  coloring 
matter  of  fat,  it  is  not  sufficiently  definite.  This  yellow  pigment, 
when  present,  is  diffused  through  all  parts  of  the  cell.  When  dilute, 
it  gives  a  yellow  hue;  when  concentrated,  orange.  It  is  found  in  the 


STRUCTURE  OF  APPENDAGES  315 

epidermis  and  in  the  fatty  masses  of  and  beneath  the  corium,  and  is 
probably  identical  with  the  yellow  color  of  fat  in  other  portions  of 
the  body  and  in  the  yolk  of  the  egg.  A  yellow  shank,  in  a  heavily 
laying  hen,  soon  loses  a  part  of  its  pigment;  this  is  also  noted  of 
the  coloring  matter  in  other  parts  of  the  body.  This  fact  indicates 
that  the  coloring  matter  of  the  fatty  part  of  the  egg  yolk  is  from 
the  same  source  as  that  of  the  fat.  The  draught  of  this  substance 
is  more  than  normally  and  the  reserve  is  being  drawn  upon.  Feed 
rich  in  zanthophyll  and  carotin  cause  intense  yellow  colored  yolks, 
and  feeds  poor  in  these  substances  cause  the  yolks  to  be  a  pale 
yellow.  Cotton  seed  meal  contains  two  pigments,  one  a  yellow 
crystalline  substance  and  the  other  a  brownish  resinous  substance. 
Both  of  these  pigments  are  probably  deposited  in  the  egg  yolk.  The 
eggs  of  some  hens  contain  a  large  quantity  giving  a  light  brownish- 
yellow  color  to  the  yolk. 

The  brown  or  black-brown  pigment  is  carried  in  microscopic 
pigment  granules,  which  may  be  scattered  through  the  ordinary 
cells  or  may  be  confined  to  special  pigment  cells.  The  former  are 
confined  to  the  epidermis;  the  latter  may  be  found  in  both  layers, 
but  infrequently  in  the  epidermis.  When  granules  are  present  in 
the  flattened  cells  of  the  corium,  they  occupy  the  nuclear  region. 
They  lie  in  short  thin  lines  while  those  of  the  under  portion  of  the 
Malpighian  layer  occur  in  oval  groups.  Where  these  granules  occur 
in  the  rete  layer,  they  cluster  around  the  nuclei.  In  the  colored 
skin  there  are  dark  pigment  granules  found  in  the  corium  and  to  a 
less  extent  in  the  rete  layer.  Hanau  has  described  a  definite  cellu- 
lar body  which  he  found  densely  packed  among  the  black-brown 
granules.  There  is  a  central  body  which  sends  out  branches  in  all 
directions.  In  very  dark  skinned  shanks  these  ramifying  strands 
interlace,  and  form  a  compact  network,  which  in  many  cases  is  so 
thick  as  to  give  the  impression  of  a  homogeneous  mass.  Here  and 
there  occur  round  or  oval  pigmented  bodies,  which  Hanau  concluded 
were  the  star-shaped  cells  with  their  pseudopod-like  appendages 
contracted.  Pigment  cells  commonly  lie  around  blood-vessels,  clearly 
indicating  their  course.  They  frequently  form  a  compact  tube,  but 
more  often  are  limited  to  fragments  which  only  partly  enclose  the 
vessels.  Pigment  cells  occur  in  several  well-defined  localities:  in  the 
upper  portion  of  the  cutis  among  the  closely  interwoven  strands  of 
connective  tissue;  in  the  region  bordering  the  blood-vessels;  in  prox- 
imity to  nerves,  in  nerve  endings  and  in  surrounding  fat  masses. 


316  ANATOMY   OF   THE  DOMESTIC  FOWL 

Isolated  granules  are  frequently  scattered  throughout  the  lower  sec- 
tion of  the  corium.  Barrows  concludes  that  the  lower  bodies  of  pig- 
ment play  little  or  no  part  in  the  color  of  the  external  shank,  as  they 
lie  far  below  the  opaque  connective  tissue.  Melanin  pigment  gran- 
ules are  always  contained  in  the  pigment  cells.  When  found  in  the 
Malpighian  layer,  the  pigment  cells  are  of  an  oval  form. 

Immediately  below  the  epidermis  in  the  shank  skin,  extends  a 
space  less  in  width  than  the  row  of  columnar  cells,  which  is  devoid 
of  pigment.  The  brown  pigment  is  melanin,  which  in  large  quanti- 
ties takes  on  a  black  hue. 

White  skin  does  not  contain  superficial  pigment.  Melanin  has 
been  observed  in  the  study  of  white  shank  skin,  but  it  lay  at  con- 
siderable depth  or  in  quantities  insufficient  to  be  noticeable.  In 
some  breeds  of  fowls,  as  the  Mottled  Houdan,  there  are  areas  in 
which  much  melanin  is  irregularly  deposited,  which  circumstance 
gives  the  leg  its  mottled  appearance. 

The  yellow  color  is  the  result  of  a  deposit  of  the  yellow  pigment 
in  the  fat  of  the  shank.  This  may  be  deposited  in  both  layers  of  the 
skin,  or  in  the  corium  alone.  When  present  it  is  diffused  throughout 
the  entire  cell  as  well  as  throughout  the  intercellular  substance. 
In  young  birds  the  Malpighian  layer  contains  much  yellow  pigment. 
Old  hens  have  only  small  quantities  in  the  corneum.  In  breeds 
with  normal  yellow  shanks  old  hens  that  have  never  laid  eggs  show 
a  deep  orange  color  in  both  the  dermis  and  epidermis. 

In  blue  shanked  birds  melanin  is  present  only  in  the  corium.  The 
black  pigment  is  seen  through  the  semi-transparent  Malpighian 
stratum,  making  it  appear  bluish  instead  of  brown  or  black. 

The  black  shank  color  results  when  melanin  appears  in  the  epi- 
dermis. Two  forms  of  black  pigment  occur  in  the  epidermis: 
granules  in  both  layers  and  pigment  cells  in  the  rete  Malpighii. 

The  green  shank  is  produced  where  there  is  pigment  in  the  epi- 
dermis and  numerous  melanin  pigment  cells  in  the  upper  corium. 
It  is  an  optical  effect  due  to  melanin  lying  under  the  semi-transparent 
yellow  epidermis.  There  is  no  melanin  in  the  epidermis. 

In  the  beak  the  corium  of  the  skin  is  represented  by  a  thin  layer 
located  between  the  periosteum  and  the  stratum  Malpighii. 
Numerous  blood-vessels  pass  into  it,  and  in  the  soft  horn-like  skin, 
occur  sensory  nerve  fibers. 

The  nails  originate  from  the  epidermis,  of  which  they  are  a 
modification.  The  nails  of  the  toes  are  bent  downward.  They 


STRUCTURE  OF  APPENDAGES  317 

present  a  convex  dorsal  surface  and  are  concave  ventrally.  The 
dorsal  surface  consists  of  a  horny  plate,  which  is  set  in  a  nail  matrix. 
The  ventral  portion  merges  with  the  sides  of  the  upper  half,  and7 
as  the  lower  portion  is  the  softer  and  wears  faster,  the  nail  has  a  sharp 
point  and  edge.  The  matrix  is  formed  by  a  growth  of  the  Malpigh- 
ian  layer  of  the  cutis.  A  fold  of  skin  lies  over  its  posterior  part. 
The  epidermic  cells  of  the  dorsal,  or  nail,  part,  and  the  base  of  the 
ventral  part  grow  fast.  The  outer  cell  layer  gradually  becomes 
horn-like. 

The  spurs  are  conical  with  a  flat  base.  The  basal  part  rests  upon 
an  enlargement  of  the  shank  bone.  Soft  structure  is  found  between 
the  horny  spur  and  the  bone.  The  upper  cells,  like  those  of  the  nails 
and  of  the  skin,  are  constantly  being  worn  or  cast  off,  and  new  cells 
push  up  from  the  lower  layers  of  cells.  These  newly  formed 
flattened  cells  soon  become  cornined.  The  oldest  formation  is 
found  at  the  tip  and  the  youngest  at  the  base. 


EMBRYOLOGY  OF  THE  CHICK 

That  a  new  individual  may  be  brought  into  existence,  there 
must  be  accomplished  the  union  of  the  male  element,  or  spermatozoon, 
with  the  female  element,  the  ovum.  This  union  is  called  fertilization. 
In  the  fowl  this  fertilization  is  accomplished  at  the  anterior  portion 
of  the  oviduct,  after  the  calyx  has  ruptured  and  discharged  its  yolk, 
and  before  the  albumen  has  been  formed  around  it.  The  blasto- 
derm is  found  on  the  surface  of  the  yolk.  One  spermatozoon  is  all 
that  is  required;  in  fact,  only  one  can  be  used  in  this  union. 

Spermatogenesis. — The  spermatozoa  are  formed  by  the  seminifer- 
ous tubules  of  the  testis.  From  these  cells,  called  the  spermatogonia, 
are  formed  other  cells  called  spermatocytes,  which  in  turn  form  the 
spermatids,  the  immediate  forerunners  of  the  spermatozoa.  During 
the  period  of  multiplication  the  spermatogonia  divide  repeatedly  by 
mitosis.  Numbers  of  small  cells  are  thus  produced,  each  containing 
in  its  nucleus  the  number  of  chromosomes  typical  of  the  somatic  cell 
of  that  fowl.  In  the  second  period  the  cells  become  larger  and 
spermatocytes  of  the  first  order  are  formed.  Then  comes  the 
period  of  maturation,  during  which  two  succeeding  divisions  rapidly 
occur.  The  first  division  results  in  the  formation  of  two  cells  exactly 
alike.  These  are  spermatocytes  of  the  second  order.  They  differ 
from  the  somatic  cells  in  that  they  contain  only  one-half  the  typical 
number  of  chromosomes.  The  second  division  produces  two  similar 
spermatids  from  one  spermatocyte  of  the  second  order.  Therefore 
four  spermatids  exactly  alike  may  be  formed  from  one  spermatocyte 
of  the  first  order.  From  these  spermatids  the  spermatozoa  are 
formed  (Fig.  55).  The  heads  of  the  spermatozoa  contain  the  nuclei 
derived  from  the  spermatids;  the  necks  contain  the  centrosomes;  and 
the  tail,  consisting  of  three  parts  is  probably  formed  from  the  proto- 
plasm. Three  parts  of  the  tail  are  as  follows:  first,  the  pars  conjunc- 
tionis,  which  unites  the  tail  to  the  neck;  second,  the  pars  principalis, 
which  constitutes  the  main  length  of  the  tail;  and,  third,  the  pars 
terminalis,  which  consists  of  an  axial  filament  which  transverses  the 
entire  tail  and  is  surrounded  by  a  protoplasmic  sheath. 

318 


EMBRYOLOGY   OF   THE   CHICK  319 

Oogenesis. — The  ovum  during  its  formation  passes  through  three 
stages. 

The  first  stage,  that  of  division,  takes  place  before  the  chick  is 
hatched,  and,  according  to  Bradley,  comes  to  an  end  about  the  time 
of  hatching.  This  stage  consists  of  the  rapid  formation  of  ova  in 
the  female  chick.  In  the  second  stage,  which  begins  about  the  time 
of  hatching,  there  is  an  increase  in  the  size  of  the  units  of  the  ovary, 
accompanied  by  yolk  formation.  At  this  time  each  ovum  is  in  its 
own  follicle  (Fig.  81),  and  is  surrounded  by  a  layer  of  cuboidal 
cells  and  a  theca.  The  theca  is  formed  from  the  adjacent  fibrous 


FIG.  81. — Section  of  ovum  in  a  hen.  i.  Nucleolus.  2.  Nucleus.  3.  Liquor 
folliculi.  4.  Stratum  granulosum.  5.  Follicular  cells.  6.  Theca  folliculi. 
7.  Peripheral  stroma. 

stroma.  The  third  stage,  that  of  maturation,  commences  during  the 
development  of  the  yolk  and  is  complete  after  it  has  escaped  to  the 
oviduct.  Maturation  consists  of  each  cell's  dividing  into  two  un- 
equal parts.  In  each  division  the  cell  is  split  into  a  small  cell  known 
as  the  polar  body,  which  is  cast  off  and  disappears,  and  a  larger  cell, 
which  is  the  ovum  proper.  In  this  process  half  of  the  original 
chromosomes  are  cast  off. 

Fertilization. — The  sperm  travels  rapidly; experiments  have  shown 
eggs  to  be  fertile  laid  twenty-four  hours  after  service  by  a  male. 


32O  ANATOMY   OF   THE   DOMESTIC   FOWL 

When  the  ovum  is  discharged  into  the  ovarian  pocket  it  is  surrounded 
by  spermatozoa. 

After  the  male  pronucleus  has  united  with  the  female  pronucleus 
in  the  single-celled  ovum,  there  is  a  cleavage  of  the  cell  in  the 
long  axis  of  the  egg,  making  two  cells;  and  then  a  cleavage  at  right 
angles,  which  progressively  continues,  makes  the  mulberry-like 
mass.  The  remaining  content  of  the  egg  consists  of  food  for  the 
development  of  the  embryo.  From  this  mass  of  cells  before  the  egg 
is  laid  the  blastoderm  is  formed.  The  cells  of  the  blastoderm  are 
differentiated  into  two  layers.  The  superficial  layer  is  the  ectoderm 
and  the  lower  layer  is  the  entoderm.  In  the  newly  laid  egg  the  blasto- 
derm may  be  observed.  It  is  about  4  millimeters  in  diameter. 
It  has  a  transparent  central  area,  the  zona  pellucida,  which  is  located 
over  the  subgerminal  region.  There  is  a  peripheral,  less  transparent 
area  called  the  zona  opaca. 

In  the  fertile  egg,  as  soon  as  it  is  subjected  to  the  proper  tempera- 
ture, cell  multiplication  in  the  blastoderm  begins.  The  first  signs 
of  such  change  are  noted  in  the  pellucid  area  of  the  blastoderm 
where  embryonal  traces  appear  in  the  form  of  the  parallel  lines 
called  the  plica  primitive,  which  diverge  to  form  the  cephalic 
dilatation.  At  about  this  time  takes  place  the  formation  of  the 
myelencephalous  columns,  in  which  the  blood  lakes  expand  in  the 
surrounding  halones  and  in  the  tracts  along  which  pass  colorless 
blood  particles.  These  tracts  extend  from  below  the  cephalic 
expansion  to  the  peripheral  sinuses,  as  the  proto-vertebrce,  which 
begin  to  appear  at  the  sides  of  the  myelon.  The  red  color  is  ac- 
quired by  the  blood,  and  the  heart  by  its  movements,  is  made  more 
manifest  as  the  punctum  saliens.  A  distinct  membrane,  the  serous 
layer,  is  formed  upon  the  germ  and  the  blastoderm.  The  cephalic 
end  of  the  embryo  rises  from  the  surface  of  the  blastoderm,  and  then, 
curving  down,  sinks  into  it,  forming  for  itself  a  kind  of  hood  of  the 
serous  layer.  This  hood  gradually  extends  from  the  margin  of  the 
fossa  over  the  body,  and,  meeting  a  similar  fold  formed  by  the 
projecting  and  incurved  tail,  closes  over  the  germ  on  the  upper  side, 
making  a  circumscribed  cavity,  which  is  the  amnion.  The  progress 
of  differentiation  of  layers  of  the  blastoderm  has  meantime,  gone  on 
beneath.  The  serous  layer  is  in  part  reflected  from  the  vascular 
and  from  the  mucous  layer.  The  mucous  layer  is  concerned  in  the 
formation  of  the  intestinal  canal;  and  beyond  this  part,  which  is  at 
first  an  open  groove,  the  mucous  layer  expands  over  the  yolk, 


EMBRYOLOGY   OF   THE   CHICK  321 

which  it  ultimately  incloses,  the  margins  of  the  mtellicle  so  formed 
contracting  and  uniting  at  the  side  opposite  the  embryo  at  a  sort_pf_ 
cicatrix,  to  which  the  last  part  of  the  abdominal  yolk  adheres.     The 
vitellicle  is  richly  vascular,  and  the  surface  next  to  the  yolk  is  aug- 
mented by  rugae. 

The  fowl's  egg,  at  about  the  fortieth  hour,  shows  the  buds  from 
which  the  limbs  are  developed.  A  vesicle  is  seen  to  protrude  near 
the  anal  end  of  the  intestine,  which,  rapidly  expanding,  spreads  over 
the  embryo,  acquiring  a  close  adhesion  to  the  amnion,  but  remaining 
distinct  from  the  vitellicle,  over  which  it  spreads.  It  finally  en- 
closes the  albumen  and  interposes  itself  between  the  latter  and  the 
lining  membrane  of  the  shell.  Umbilical  vessels  are  associated  with 
this  membrane.  Hunter  called  this  membrane  the  allantois  from 
its  containing  urine,  and  Owen  states  that  the  sac  which  surrounds 
the  albumen  acts  as  the  chorion  or  placenta;  for  it  is  most  probable 
that  from  this  surface  the  albumen  is  absorbed  and  the  chick  sup- 
ported on  its  developmental  food.  The  external  part  of  the  sac 
apparently  acts  as  lungs  as  it  comes  into  contact  with  the  shell  of 
the  egg  through  pores  of  which  there  is  an  exchange  of  air.  Oxygen 
is  consumed  and  carbon  dioxide  is  given  off.  The  blood  in  the 
vessels  of  this  membrane  is  in  color  more  like  arterial  blood  and  that 
in  the  interior  more  like  venous  blood. 

The  embryonic  mass  of  the  incubating  egg  always  floats  to  the  top 
side.  As  the  embryo  grows  it  turns  upon  its  left  side,  exhibiting  a 
profile  view;  it  then  indents  the  yolk,  and  finally  almost  divides  it 
into  two  parts. 

The  peripheral  layers  of  cells  rise  from  the  margin  of  the  germ 
mass,  and  extend  and  contract  toward  the  opposite  pole.  This 
tract  of  germ  substance  is  the  primitive  streak.  Along  the  median 
line  it  next  forms  a  furrow,  which  stops  short  of  the  ends  of  the  streak. 
This  streak  terminates  opposite  the  point  from  which  the  germ 
begins,  and  swells  into  the  head.  The  median  furrow  expands  upon 
it.  The  cephalic  borders  are  next  united  by  a  thin  layer  of  epithelial 
cells  above  the  furrow,  converting  it  into  a  cavity,  or  ventricle.  The 
myelonal  furrow  is  similarly  convered  by  a  layer,  uniting  the  lateral 
columns.  The  embryonal  trace  becomes  longer,  narrower,  and 
bends  round  the  vitellus.  A  layer  of  epithelial  cells  forms  a  net- 
work over  the  whole  dorsal  surface  of  the  embryo.  Oblique  striae 
appear  in  the  broadening  germ  mass  radiating  from  the  primitive 
streak.  These  indicate  divisional  segments.  These  beginnings 
21 


322  ANATOMY    OF   THE   DOMESTIC   FOWL 

of  aponeurotic  septa  probably  accompany  and  support  nervous 
productions  from  the  myelon  columns. 

Two  transverse  constrictions  begin  to  divide  the  cephalic  en- 
largements into  three  lobes,  the  second  and  the  third  of  which  ex- 
pand into  vesicles.  An  accumulation  of  cells  at  the  side  of  the 
middle  expansion  appears  to  add  greatly  to  its  breadth.  This 
forms  the  basis  of  the  eyes. 

The  differentiation  and  the  confluence  of  the  cell  constituents 
of  the  primitive  streak  have  led  to  the  formation  of  a  pair  of  albu- 
minous cords  along  the  sides  of  the  median  furrow,  forming  the 
myelon  proper.  The  cells  exterior  to  and  above  them  are  converted 
into  muscle  and  fibrous  septa;  and  beneath  the  column  is  a  jelly- 
filled  cylinder,  with  a  transversely  striated  sheath,  pointed  at  both 
ends,  forming  the  notocord.  Its  anterior  point  passes  a  little  in 
advance  of  the  acoustic  vesicle.  Beneath  the  notocord  and  sur- 
rounding the  blastema  is  stretched  the  vegetative,  or  mucous,  layer 
of  cells,  in  contact  with  the  yolk.  Both  the  head  and  the  tail 
of  the  now  cylindrical  embryo  are  liberated  from  the  surface  of  the 
yolk.  A  fold  of  the  blastema,  reflected  from  the  under  part  of  the 
head,  sinks  like  a  pouch  into  the  yolk,  and  soon  includes  the  rudi- 
ment of  the  heart,  like  a  bent  cord,  which  begins  to  oscillate  about 
the  seventh  day.  From  the  midline  of  the  inferior  surface  of  the 
embryo,  or  its  mucous  layer,  two  longitudinal  plates  descend,  diverg- 
ing into  the  yolk-substance,  and  form  the  primitive  intestinal  groove. 
The  ophthalmic  vesicle  elongates  and  curves  outward  until  the 
two  ends  almost  come  into  contact.  Between  these  two  ends  and 
beneath  the  delicate  tegumentary  layer  connecting  them  the  crystal- 
line lens  is  formed.  About  the  same  time,  the  otoliths  appear  in. 
the  acoustic  vesicles,which  have  now  acquired  a  cartilaginous  case. 
The  cerebral  lobes  begin  to  be  formed  by  a  small  fold,  rising  laterally 
and  overlapping  the  forepart  of  the  second  enlargement,  which 
has  expanded  to  greater  breadth.  The  olfactory  cavities  appear  as 
small  cutaneous  follicles. 

The  two  myelonal  columns,  expanding  between  the  ear  sacs  and 
receding  so  as  to  show  the  notocord  beneath,  bend  upward  and 
inward,  and  unite,  to  be  continued  into  the  posterior  of  the  optic 
lobes,  thus  commencing  the  cerebellar  bridge  across  the  epencephalic 
ventricle.  The  encephalic  vacuities  have  begun  to  be  filled  by  the 
granular  basis  of  the  cerebellar  substance. 

The  intestinal  groove  begins  to  be  converted  into  a  canal  at  its 


EMBRYOLOGY   OF   THE   CHICK  323 

two  ends.     Beneath  the  anterior  end,  and  behind  the  heart,  there 
gradually  accumulates  the  cellular  basis  of  the  liver. 

The  commencement  of  the  development  of  the  organ  of  hearing 
is  by  a  superficial  depression  of  the  cephalic. blastema  to  meet  the 
process  from  the  encephalon,  which  forms  the  acoustic  nerve. 
The  lining  of  the  depression  becomes,  on  closure  of  the  slit,  the 
proper  tunic  of  the  labyrinth. 

The  vesicle  of  the  labyrinth  swells  into  four  dilatations,  of  which 
three  are  ampullar  and  the  fourth  cocr^lear.  The  ampullar  dilata- 
tions extend  into  very  slender  canals,  at  first  almost  in  the  same 
plane,  by  which  they  are  brought  into  mutual  communication. 
As  the  canals  expand  and  elongate,  they  assume  their  characteristic 
relative  positions  as  external,  superior,  and  posterior,  the  posterior 
end  of  the  external  canal  being  extended  beneath  the  posterior 
canal.  The  cochlear  dilatation  curves  as  it  elongates.  An  inner 
layer  becomes  distinct  from  the  common  membrane  and  forms  the 
acoustic  lamina. 

As  in  the  development  of  the  ear,  so  in  the  development  of  the 
eye,  the  production  of  the  nerve  process  from  the  cerebral  center 
is  the  first  step;  the  infolding  of  the  superficial  blastema  to  meet 
the  nerve  is  the  next.  The  so-called  cutaneous  follicle  becomes  a 
circumscribed  sac  or  vesicle,  in  which  the  changes  and  the  develop- 
ment next  proceed,  converting  the  vesicle  into  an  acoustic  labyrinth 
or  into  an  eyeball.  In  each  case  neural  elements  of  two  vertebrae 
become  modified  to  lodge  and  to  protect  the  sense  organs,  forming 
respectively  the  recess  called  otocrane  and  that  called  the  orbit. 
The  one  is  located  between  the  occipital  and  the  parietal  vertebras, 
and  the  other  between  the  frontal  and  the  nasal  vertebrae.  The 
part  of  the  outer  blastemal  layer  of  the  head  which  sinks  to  meet 
the  process  from  the  mesencephalic  dilatation,  rapidly  changes  its 
f  ollicular  into  a  vesicular  state.  The  vesicle  thus  formed  elongates, 
bending  around  the  cell  mass  in  which  the  crystalline  lens  is  formed, 
and  the  meeting  of  the  two  ends  results  in  forming  the  choroid 
fissure  at  the  lower  part  of  the  eyeball. 

The  mesencephalic  process,  or  optic  nerve,  expands  at  the  posterior 
of  the  circular  sac,  and,  in  the  course  of  mutation  into  eyeball, 
lines  its  posterior  part  with  a  layer  which  becomes  the  retina.  The 
transparent  layer  covering  the  forepart  of  that  sac  and  the  inclosed 
lens  is  formed  into  the  cornea.  Other  layers  of  the  sac  are  formed 
into  the  choroid,  the  ciliary  processes,  the  iris,  and  the  pecten. 


324  ANATOMY    OF    THE   DOMESTIC   FOWL 

Of  the  appendages  of  the  eye  the  membrana  nictitans  is  the  first 
to  develop.  Then  develop  the  lower  lid  and,  last,  the  upper  lid. 

After  the  development  of  the  essential  organs  of  sense,  the  skin 
is  developed.  Modifications  of  the  skin  form  the  outer  ear  and  the 
eyelids.  Then  are  formed  the  maxillary  arch,  the  hyoidean 
arch,  and  the  scapular  arch. 

The  vessels  which  return  the  blood  from  the  vitellicle  are  the 
transverse  and  the  longitudinal  vitelline  veins.  The  first  are  so 
called  because  these  trunks  pass  to  the  embryo  at  right  angles  to  its 
axis.  They  are  the  largest  returning  canals.  The  longitudinal  veins 
extend  parallel  with  the  axis  of  the  embryo;  they  are  of  smaller  size. 
The  right  anterior  longitudinal  vein  becomes  the  right  precaval  and 
receives  the  remains  of  the  right  transverse  vitelline  vein,  as  the 
right  vena  azygos.  The  left  anterior  longitudinal  vitelline  vein  is 
also  persistent  as  the  left  precaval,  and  enters  in  the  mature  bird, 
as  in  the  embryo,  at  the  posterior  or  the  lower  part  of  the  auricle. 
The  left  transverse  vitelline  vein  is  also  subsequently  reduced,  by 
receiving  only  the  vertebral  veins  of  that  side,  to  the  condition  of  a 
so-called  azygos  vein.  The  main  trunk  of  the  post-caval  is  the  result 
of  the  returning  vessels  from  the  abdominal  viscera  and  the  posterior 
limbs  at  a  later  stage  of  development.  There  is  but  one  principal 
posterior  longitudinal  vitelline  vein,  and  this  anastomoses  with  the 
left  transverse  vein  as  it  enters  the  embryo. 

The  auricle,  which,  by  its  dilatation  of  the  left  side,  appears  to  be 
double,  receives  the  venous  blood  at  its  right  division.  The  left 
one,  subsequently  receives  the  veins  from  the  lungs,  is  ultimately 
separated  from  the  left  precaval  and  the  right  auricle  to  which  that 
vein  is  conducted  and  restricted. 

The  ventricular  part  of  the  heart,  at  the  second  day  of  incubation, 
is  in  the  form  of  a  bent  tube,  curving  from  behind  downward,  for- 
ward, to  the  right  and  upward,  continuing  insensibly  into  the  part 
representing  the  aortic  bulb,  in  which  the  septum  first  appears,  and 
ultimately  dividing  the  ventricle  into  two. 

At  this  stage  the  piers  of  the  maxillary  arch  appear  as  buds 
from  beneath  the  eyeballs.  The  naso-premaxillary  process  is  above- 
their  interspace.  The  piers  of  the  mandibular  arch  and  those  of 
the  hyoidean  arch  follow  in  close  succession.  The  blastemal  base 
of  the  scapular  arch  projects  slightly  at  the  sides  of  the  fovea 
cardiaca;  the  piers,  now  separate,  ultimately  meet  in  front  of  the 
heart,  and  accompany  it  in  its  retrograde  course.  The  mesen- 


EMBRYOLOGY    OF    THE    CHICK  325 

cephalon  is -the  largest  of  the  segments  of  the  brain  which  are  con- 
nected with  the  eyeballs. 

When  the  heart  has  assumed  its  form  as  such,  distinct  frpmjthe 
great  trunks  rising  from  it,  the  two  arteries  from  the  base  of  the 
ventricles  appear.  The  artery  to  the  right  bifurcates,  one  division 
supplying  the  head  and  the  wings,  the  other  winding  over  the  right 
bronchus.  That  to  the  left  also  bifurcates.  Its  left  division  arching 
over  the  left  bronchus  and  anastomosing  with  the  right  arch  a  little 
below  and  behind  the  apex  of  the  heart.  Its  right  division  arches 
over  the  back  of  the  heart,  bending  to  the  right  and  anastomosing 
with  the  right  aortic  arch  just  above  the  outer  ductus  arteriosus. 
Each  of  these  divisions  of  the  left  primary  arterial  trunks  sends  off 
a  branch  to  its  corresponding  lung.  As  the  lung  expands,  and 
especially  at  the  beginning  of  the  act  of  expansion  toward  the  close 
of  the  period  of  incubation,  the  blood  is  diverted  into  the  pulmonary 
vessels,  and  the  channels  below  them  shrink  and  disappear.  The 
left  primary  artery  is  retained  as  the  trunk  of  the  pulmonaries,  and, 
through  the  changes  in  the  interior  of  the  ventricle,  this  artery  comes 
to  discharge  exclusively  the  ventricle  corresponding  to  the  right  in 
mammals.  The  retained  aorta  rises  from  the  left  ventricle. 

The  air-sacs  begin  at  the  lower  point  of  the  lung,  appearing  like 
small  hydatids,  and  extend  further  and  further  into  the  abdomen, 
in  front  of  the  kidneys.  They  are  at  first  full  of  fluid.  Soon  after 
the  development  of  the  abdominal  air-sacs  others  are  developed. 

The  lungs  are  at  first  free,  but  afterward  begin  to  be  attached  to 
the  ribs  and  to  the  spine. 

In  the  female  embryo  we  first  observe  two  oviducts,  one  on  each 
side  of  the  basis,  or  stroma  of  the  ovarium,  which  appears  in  a 
relation  to  the  primordial  kidneys  similar  to  that  of  the  testes  in  the 
male.  At  the  period  when  the  permanent  kidneys  have  sent  their 
ureters  to  the  cloaca,  the  oviducts  have  been  developed  as  prolonga- 
tions from  that  part,  and,  up  to  a  certain  point  of  development,  they 
are  of  equal  size  and  length.  Subsequently  the  left  oviduct  alone 
continues  to  grow;  the  right  remaining  stationary  or  shrivels; 
occasionally  it  may  be  discerned  as  a  rudimentary  in  the  mature 
bird,  but  usually  all  trace  of  it  has  disappeared  before  hatching. 
The  left  oviduct  expands  above  or  at  its  free  end  into  the  infundibular 
orifice,  where  its  parietes  are  very  thin.  As  it  descends,  these  in- 
crease in  thickness,  and  the  efferent  tube  gradually  acquires  the 


326 


ANATOMY   OF   THE   DOMESTIC   FOWL 


FIG.  82. — Embryological  studies. 

A.  i,  The  chorion  and  allantois.     2,  The  allantoic  cavity.     3,  The  amnion. 

4,  The  yolk  sac.     5,  A  small  quantity  of  remaining  albumin. 

B.  Brain  tube  of  a  chick  25^  hours  old  showing  partly  closed  brain  tube  with 
eleven  folds  of  neuromeres. 

C.  The   development   of  the   alimentary  tract,     i,    Trachea.     2,   Lung.     3, 
Esophagus.     4,  Stomach.     5,  Pancreas.     6,  Bile  duct.     7,  V-shaped  loop  of  mid- 
gut.     8,  Cloaca.     9,  Vitello-intestinal  duct. 

D.  i  to  6  inclusive,  same  as  C.  7,  Caeca.     8,  Cloaca. 

E.  Kidneys,  Wolffian  bodies,  and  testes  of  an  embryo  chick,     i,  The  adrenals. 
2,  The  genital.     3,  Primitive  oviduct.     4,  Permanent  kidney.     5,  Ureters.     6, 
Duct  of  primitive  kidney  which  conducts  the  excretion  into  the  cloaca. 

F.  A  transverse  section  of  a  chicks'  head  48  hours  of  incubation,     i,  Fore- 
brain.     2,  Pigmented  layer  of  retina.     3,  Ectoderm.     4,  Nervous  part  of  retina. 

5,  Optic  stalk.     6,  Invagination  of  ectoderm  to  form  the  lens  rudiment. 


EMBRYOLOGY   OF    THE    CHICK  327 

texture  and  form  of  an  intestine.  It  is  attached  and  supported  by  a 
duplicature  of  the  peritoneum. 

At  first,  the  right  and  the  left  ovaria  are  similar  in  size,  but  the 
symmetry  is  soon  disturbed  by  concentration  of  development  in  the 
left  ovary.  The  right  ovary  remains  stationary  and  ultimately, 
in  most  birds,  completely  disappears  by  the  time  the  chick  is  ready 
to  emerge  from  the  shell. 

Three  fetal  membranes  are  developed,  the  chorion,  the  amnion, 
and  the  allantois.  There  is  also  developed  the  yolk  sac  (Figs.  82  and 
83).  The  amnion  is  connected  to  the  body  wall  at  the  umbilicus. 
The  amniotic  fluid  is  found  in  this  sac.  The  chorion  is  at  first 
surrounded  by  the  albumen,  but  as  the  albumen  is  absorbed  the 
chorion  comes  in  contact  with  the  inner  shell  membrane.  It  is 
probable  that  the  chorion  consists  of  ectoderm  on  the  outside  and  of 
mesoblast  on  the  inside.  The  amnion,  on  the  other  hand,  is  formed 
of  mesoblast  on  the  outside  and  ectoderm  on  the  inner,  or  embryonal, 
side.  The  allantois  springs  from  the  embryo  soon  after  the  fourth 
day,  and  develops  from  the  ventral  wall  of  the  primitive  gut.  By 
some  embryologists,  the  yolk  sac  is  included  in  the  embryonic  mem- 
branes. It  commences  as  the  splanchno-pleure  surrounding  the 
mass  of  yolk.  It  becomes  smaller  as  the  yolk  is  absorbed.  At  first 
its  outline  is  round  but  later  its  .walls  become  folded  in.  The  yolk  is 
dissolved  and  absorbed  by  the  entodermic  lining  of  the  sac,  and  is 
carried  to  the  embryo  by  veins  called  the  vitelHne  veins  (Fig.  83,  No. 
B,  4),  which  ramify  on  the  walls  of  the  sac. 

Some  time  after  the  fourteenth  day,  the  chick  assumes  a  position 
lengthwise  within  the  egg  shell  so  that  the  head  is  near  the  broad 
end  of  the  egg.  The  head  is  bent  upon  the  chest  and  the  beak  is 
usually  tucked  under  the  wing.  Later  the  head  assumes  a  position, 
by  a  double  curve  of  the  neck,  so  that  the  beak  is  in  contact  with  the 
air  cell.  About  the  fifteenth  day,  the  coils  of  intestine,  which 
heretofore  have  been  outside  the  abdominal  cavity,  are  withdrawn 
into  the  abdominal  cavity,  as  is  also  the  abdominal  yolk  sac.  As  the 
chick  pips  out  of  the  shell,  the  umbilicus  becomes  occluded. 

The  outer  upper  part  of  the  tip  of  the  beak  is  provided  with  a 
short,  stout,  spike-like  arrangement,  called  the  egg  tooth.  On  the 
twentieth  day  this  part  of  the  beak  is  forced  against  the  wall  of  the 
egg  and  gradually  breaks  through  the  egg  shell.  The  breathing  by 
the  lungs  commences  some  time  before  hatching;  this  is  evidenced  by 
the  chick  within  the  shell  giving  chirping  sounds. 


ANATOMY   OF   THE  DOMESTIC  FOWL 


FIG.  83. 

A.  Longitudinal  section  of  chick,   4  days  incubation,      i,  Cephalic  fold.     2, 
Caudal  fold.     3,  True  amniotic  cavity.     4,   Epiblast.     5,  Somatic  mesoblast.     6, 
Visceral  mesoblast.     7,  Hypoblast.     8,  Future  anua  still  closed.     9,  The  allan- 
toic  vessicle.      10,  The  mesentery,     n.  Intestine.     12  and   13,  Yolk  sac.     14, 
Cavity   of  true  amnion.     15,  The  mouth.     16,   Pleuro-peritoneal  cavity.     17, 
Fore  gut. 

B.  Membranes  of  the  chick  at  the  third  day  of  incubation,     i.   Membrane 
surrounding  albumin.     2,  Amnion.     3,  Allantois.     4,  Vitellicle. 

C.  The  fore  part  of  an  embryo  chick  at  the  second  day.     i,  Mesencephalon. 
2,    The   eye.     3,   Olfactory   organ.     4,    Mandibular  arch.     5,    Maxillary  arch. 
6,  Maxillary  arch.     7,  Hyoidean  arch.     8,  Scapular  arch.     9,  Depression  organ 
of  hearing,     n,  Process  from  encephalon  for  union  with  nerve  of  hearing. 

D.  Primitive   blood-vessels  at  second  day  of  incubation  (Owen),     i,   Meso- 
cephalon.     2,  The  right  anterior  longitudinal  vein.      3,  The  eye.     4,  The  man- 


EMBRYOLOGY   OF    THE   CHICK  329 

The  circulation  of  the  blood  is  somewhat  like  the  circulation  in  the 
fetus  of  quadrupeds.  The  primitive  tubular  heart  (Fig.  83,  No.  D, 
8)  is  bent  in  S-shape;  the  two  ends  are  connected  with  blood-vessel?; 
and  later,  by  the  development  of  the  septa,  the  cavities  of  the  adult 
heart  are  denned.  The  foramen  ovale  is  found  in  the  median 
septum.  This  opening  brings  the  right  and  the  left  side  into  commu- 
nication. The  septa  between  the  cavities  of  the  heart  are  completed 
by  the  end  of  the  sixth  day.  The  two  vitelHne,  or  omphalo-mesen- 
teric,  veins  carry  the  blood  containing  the  nutrients  from  the  yolk 
sac  to  the  liver,  where  it  is  mixed  with  the  blood  drained  from  the 
intestines  by  the  portal  vein,  and  this  blood  is  finally  carried  by 
the  posterior  vena  cava  into  the  right  auricle  of  the  heart.  From 
here  it  passes  through  the  foramen  ovale  to  the  left  auricle;  from  the 
left  auricle  it  enters  the  left  ventricle,  from  which  it  is  forced  into 
the  aorta,  and  then  out  into  the  systemic  circulation.  Practically 
all,  if  not  all,  of  the  blood  of  the  pulmonary  artery  is  sent  into 
the  aorta  through  a  connection  with  this  vessel  called  the  ductus 
arteriosus. 

Down  appears  about  the  thirteenth  day  of  incubation.  There  are 
two  kinds  of  down  on  the  chick,  one  long,  which  comes  first,  about 
two  or  three  days  before  hatching;  a  second,  or  fine,  down  forms  at 
the  roots  of  the  other.  As  the  embryo  develops  the  air  cell,  at  the 
large  end  of  the  egg  which  is  developed  between  the  two  shell 
membranes,  or  membrance  putamince,  gradually  enlarges. 

dibular  arch.  5,  The  hyoidean  arch.  6,  Scapular  arch.  7,  The  same.  8,  The 
ventricular  portion  of  the  heart.  9,  The  right  transverse  vitelline  vein.  10, 
Posterior  longitudinal  vitelline  vein,  n,  Vertebral  vein.  12,  Tributaries  of 
same.  14,  The  auricle.  16,  Aortic  bulb. 

E,  A  transverse  section  of  chick  embryo,   29  hours  incubation.     I,    Neural 
canal.     2,  Neural  crest.     3,  Somatopleure.     4,  Splanchnopleure.     5,  Omphalo- 
mesenteric  vein.     6,  Aorta.     7,  Notocord.     8,  Pleuroperitoneal  cavity. 

F.  Chick  embryo  at  the  ninth  day  of  incubation,     i,  Allantois.     2,  Amnion. 
3,  Air  cell  at  large  end  of  the  egg.     4,  Egg  shell.     5,  Outer  shell  membrane.     6, 
Inner  shell  membrane.     7,  Yolk  sac.     8,  Albumin  (Bradley). 


OUTLINE  FOR  LABORATORY  STUDY  OF  THE  CHICK 

The  objects  of  laboratory  study  of  the  embryos  are  as  follows: 

1.  To  study  the  living  embryo. 

2.  To  study  the  entire  embryo: 

With  the  dissecting  microscope,  as  an  opaque  object. 
With  the  compound  microscope  after  killing,  hardening,  clarifying, 
and  mounting. 

3.  To  study  embryos  by  dissection,  in  later  stages. 

4.  To  study  the  serial  sections  with  the  compound  microscope. 

THE  LIVING  EMBRYO 

The  egg  is  opened  under  warm  physiological  salt  solution:  0.8 
per  cent,  sodium  chlorid  in  distilled  water  heated  to  a  temperature 
of  38°C. 

Gradually  pick  away  the  shell  at  the  large  end.  Note  that  there 
are  two  membranes  and  an  air  cell.  Strip  of  the  membranes. 
When  sufficient  shell  and  membranes  have  been  removed  from  the 
large  end,  invert  the  open  end  of  the  egg  in  the  salt  solution  and 
allow  the  contents  to  flow  out.  Care  must  be  taken  not  to  break  the 
yolk.  The  embryo,  or  blastoderm,  lies  upon  the  surface  of  the 
yolk,  which  is  usually  turned  with  this  body  uppermost.  Separate 
the  blastoderm  by  cutting  around  the  outside  of  the  area  vasculosa. 
In  doing  this  a  small  pair  of  slightly  curved  scissors  is  needed.  After 
the  embryo,  or  blastoderm,  has  been  separated,  gently  float  it  into 
a  watch  crystal  with  the  flat  bottom  submerged  in  the  salt  solution. 
The  watch  crystal  with  its  contents  may  now  be  gently  lifted  out. 
Next  remove  the  vitelline  membrane.  The  vitelline  membrane  is 
the  delicate  transparent  membrane  covering  the  blastoderm.  The 
embryo  is  now  ready  for  study. 

THE  PREPARATION  FOR  STUDY  OF  ENTIRE  EMBRYOS  AND  SECTIONS 

The  following  processes  may  be  used  in  killing  embryos  up  to 
four  days,  or  ninety-six  hours,  of  age.  After  removing  the  embryo 
as  described  above,  spread  the  blastoderm  out  in  the  watch  crystal 
and  pipette  off  the  salt  solution.  Allow  it  to  stand  till  the  edge  of 

330 


OUTLINE   FOR   LABORATORY   STUDY   OF   THE   CHICK        331 

the  tissue  begin  slightly  to  adhere.  Then  slowly  add  the  killing 
fluid  by  aid  of  a  pipette,  dropping  it  on  the  center  of  the  embryo. 
The  pipette  must  be  held  low  or  the  mechanical  interference~wiH 
dislocate  the  parts. 

Older  embryos  are  submerged  with  their  membranes  intact  into 
the  killing  fluid.  The  quantity  of  fluid  should  be  several  times  the 
bulk  of  the  specimen.  Kleinenberg's  picrosulphuric  acid  may  be 
used  as  a  killing  fluid.  This  fluid  is  a  saturated  solution  of  picric 
acid  plus  2  per  cent,  sulphuric  acid,  to  which  is  added  twice  its 
volume  of  water. 

Chick  embryos  from  one  to  two  days  old  should  be  left  in  this 
fluid  from  one  and  one-half  to  six  hours.  Embryos  from  two  to 
four  days  old  two  and  one-half  to  six  hours.  Remove  the  specimen 
from  the  killing  fluid,  and  place  it  in  70  per  cent,  alcohol.  Change 
the  alcohol  every  twenty-four  hours  until  the  color  ceases  to  come 
out  of  the  embryo.  Preserve  in  80  per  cent,  alcohol. 

If  the  specimen  is  to  be  mounted  whole,  transfer  it  from  80  per 
cent.,  then  to  50  per  cent.,  then  to  35  per  cent.,  and,  finally  to 
water.  Small  embryos  should  remain  in  each  fluid  thirty  minutes 
and  large  ones  sixty  minutes. 

The  following  method  may  be  used  for  staining  embryos:  Dilute 
Delafield's  hematoxylin  with  four  times  its  volume  of  water.  To 
every  6  cubic  centimeters  of  this  diluted  hematoxylin,  add  one  drop 
of  Kleinenberg's  undiluted  picrosulphuric  acid,  and  leave  specimen  in 
the  fluid  thus  prepared  until  it  is  stained  through.  This  will  require 
from  one  to  three  hours.  Now  pass  up  through  the  series  of  alcohols 
to  70  per  cent.  Next  extract  the  excessive  stain  with  i  per  cent, 
hydrochloric  acid  in  70  per  cent,  alcohol.  Wash  repeatedly  with 
70  per  cent,  alcohol  to  free  from  the  acid;  then  transfer  the  specimen 
to  80  per  cent,  alcohol  and  leave  in  this  for  several  hours  for  com- 
plete removal  of  the  acid;  then  transfer  to  95  per  cent,  alcohol  for 
thirty  minutes.  Allow  the  specimen  to  remain  in  absolute  alcohol 
for  one  hour.  Introduce  a  layer  of  oil  of  cloves  or  xylol  beneath  the 
alcohol.  This  may  be  done  by  gradually  allowing  the  fluid  to  run 
down  the  side  of  the  bottle.  After  the  embryos  have  sunk  into  the 
oil  and  begun  to  appear  transparent,  remove  the  fluid  and  add  fresh 
oil.  After  the  specimen  is  sufficiently  transparent,  mount  in 
balsam,  supporting  the  cover  slip  so  that  it  will  not  rest  on  the 
embryo. 

In  staining  for  section,  place  the  embryo  in  borax  carmine  from 


33 2  ANATOMY   OF   THE   DOMESTIC   FOWL 

the  50  per  cent,  alcohol  and  leave  twelve  hours.  Then  wash  in  50 
per  cent,  alcohol;  after  which  transfer  to  70  per  cent,  alcohol  for  six 
hours.  Clarify  in  oil  of  cedar  or  oil  of  cloves,  and  place  in  melted 
paraffin  for  two  hours.  Imbed  in  paraffin,  and  section. 

Embryos  may  be  hardened,  imbedded,  and  sectioned  after  the 
usual  methods,  using  either  paraffin  or  celloidin,  and  the  sections 
stained  with  hematoxylin  and  eosin  after  sectioning. 

POINTS  TO  BE  OBSERVED  IN  THE  STUDY 

I.  THE  EMBRYO  TWENTY-NINE  TO  THIRTY-FOUR  HOURS  OLD  WITH 
FROM  TEN  TO  FOURTEEN  SOMITES. 

A  study  of  the  egg. 

In  opening  the  egg,  observe  that  the  shell  membranes  are  double. 

Observe  that  the  shell  is  porous. 

Note  the  air  cell  at  the  large  end  of  the  egg  and  note  that  the  space 
or  cell  lies  between  the  outer  and  the  inner  shell  membrane. 

After  the  egg  contents  have  dropped  into  the  salt  solution,  note 
extending  from  the  ends  of  the  yolk  the  twisted  denser  cords  of 
albumen.  These  are  the  chalazge,  which  act  as  stays  to  the  yolk. 
Note  that  the  yolk  is  surrounded  by  a  delicate  membrane.  This 
is  the  vitelline  membrane.  The  yolk  is  the  true  ovum  and  serves 
as  food  for  the  developing  embryo. 

A  study  of  the  living  embryo. 

Note  the  amount  of  yolk  that  is  covered  by  the  blastoderm. 
Note  the  slipper-shaped,  transparent  center  of  the  blastoderm. 
This  is  the  area  pellucida.  In  the  center  of  this  there  is  a  narrow 
white  streak.  The  area  opaca  is  the  area  lying  external  to  the  area 
pellucida.  In  this  there  is  the  area  vasculosa. 

A  study  of  the  embryo  entire,  including  the  vascular  area. 

The  blood  islands  show  as  irregular  deeply  stained  masses  in  the 
vascular  area.  At  this  stage  they  are  inclosed  in  wide  anastomosing 
tubes,  the  extra-embryonic  blood-vessels,  which  open  peripherally 
into  the  bounding  sinus  terminalis. 

The  following  structures  may  be  identified: 

The  neural  tube  forming  the  axis  of  the  embryo.  In  the  anterior 
region  may  be  noted  the  forebrain,  the  optic  vesicles,  the  midbrain. 
The  hindbrain  is  subdivided  into  the  neuromeres.  The  cord,  or 
myelon,  of  the  neural  tube  back  of  the  hindbrain  is  closed  in  front 
but  is  open  behind. 


OUTLINE   FOR   LABORATORY    STUDY    OF    THE    CHICK         333 

The  head  projects  above  the  blastoderm.  The  fold  which  unites 
the  ventral  surface  of  the  head  with  the  blastoderm  is  called  the 
head  fold. 

The  diverging  folds  of  the  myelon  encloses  the  primitive  streak. 

On  each  side  of  the  neural  tube  are  the  mesoblastic  somites.  The 
series  is  continued  behind  by  the  undivided  segmental  plate. 

The  heart  is  beneath  the  hindbrain.  The  portion  of  the  body 
cavity  in  which  it  lies,  is  bounded  in  front  by  the  head  fold  and  behind 
by  the  diverging  limbs  of  the  splanchno-pleure.  Its  posterior  or 
venous  end  receives  the  vitelline  veins  from  the  vascular  area.  The 
anterior  or  arterial  end  is  prolonged  into  the  ventral  aorta. 

Note  that  the  axis  is  somewhat  bent. 

The  head  fold  of  the  amnion  is  noted  to  extend  over  the  anterior 
end  of  the  head. 

A  study  of  the  transverse  sections.  * 

The  sections  about  20  micro-millimeters  thick  should  be  cut  serially, 
and  so  mounted.  Knowing  how  many  micro-millimeters  the 
embryo  is  in  length  will  enable  one  to  make  a  diagram  of  the  fetal 
structure  in  the  study  of  the  series  of  transverse  sections.  The 
sections  should  be  drawn  in  the  order  studied  so  as  to  obtain  relative 
structural  ideas. 

With  the  microscope  study  the  following  regions: 

1.  Optic  vesicle. 

2.  Midbrain. 

3.  Posterior  half  of  the  heart. 

4.  Myelon  in  the  closed  region. 

5.  Myelon  in  the  open  region. 

6.  Through  the  primitive  streak. 

2 .    THE  EMBRYO  TWENTY  TO  TWENTY-FOUR  HOURS  OLD  WITH  FROM 

TWO  TO  six  SOMITES". 

Compare  the  parts  in  this  embryo  with  those  of  the  embryos  from 
twenty-nine  to  thirty-four  hours  old.  Note  and  describe  the  rela- 
tions of  the  embryo,  the  area  pellucida,  and  the  area  opaca.  Note 
how  much  of  the  yolk  the  blastoderm  covers. 

In  studying  the  entire  embryos,  note  the  condition  of  the  medul- 
lary plate.  Observe  if  the  tube  is  formed  in  any  part;  how  far  back 
the  head  plate  extends,  if  the  heart  can  be  seen;  and  if  the  primitive 
streak  is  longer  or  shorter  than  in  i. 

Study  relations  of  structures  and  make  drawings  through  the  point 


334  ANATOMY   OF   THE   DOMESTIC   FOWL 

of  divergence  of  the  walls  of  the  fore  gut;  also  through  the  somatic 
region,  and  through  the  primitive  streak. 

Study  all  parts,  as  the  head  fold,  the  heart,  and  the  fore  gut. 

3.  THE  EMBRYO  FORTY-FOUR  TO  FORTY-EIGHT  HOURS  OLD  WITH 
TWENTY-FOUR  TO  TWENTY-NINE  SOMITES. 

Remove  the  embryo  with  the  entire  area,  and  preserve  it. 

Note  and  carefully  describe  the  changes  visible  to  the  naked  eye 
since  the  thirty-fourth  hour. 

In  making  a  study  of  the  entire  embryo  we  note  there  has  been  a 
rapid  growth  of  the  dorsal  surface  of  the  head,  which  has  become 
more  bent.  This  bend,  in  the  region  of  the  midbrain  is  called  the 
cephalic  flexure.  The  forebrain  and  part  of  the  midbrain  form 
almost  a  right  angle  with  the  rest  of  the  head.  The  head  is  com- 
pressed laterally  and  free  from  the  blastoderm.  The  dorsal  side 
of  the  trunk  is  turned  up,  and  there  is  a  twisting  of  the  axis  of  the 
embryo  just  back  of  the  heart.  The  tail  fold  begins  at  about  this 
time  and  may  or  may  not  be  visible.  The  optic  vesicles  are  rela- 
tively smaller  in  relation  to  the  brain  than  in  i.  Note  the  part 
of  the  forebrain  to  which  they  are  attached.  Observe  the  inner  and 
outer  layers  of  the  retina,  the  lens,  the  choroid  fissure,  and  the 
cavity  of  the  vitreous  humor. 

Note  the  auditory  vesicles  and  whether  or  not  they  are  closed  sacs. 

Note  that  the  heart  has  grown  in  length  and  has  become  doubled 
on  itself.  The  two  ends  are  fixed.  Note  the  relation  of  the  heart 
to  the  afferent  and  efferent  blood-vessels.  Note  that  two,  and 
possibly  three,  visceral  pounches  are  visible.  Note  whether  or  not 
they  are  ventral  to  the  midbrain.  The  first,  the  hyomandibular 
pouch,  is  bounded  in  front  by  the  first  visceral,  or  mandibular,  and 
behind  by  the  second  visceral,  arch.  The  second  pouch  is  bound  in 
front  by  the  hyoid,  and  behind  by  the  third  visceral  arch.  The 
third  pouch  is  bounded  in  front  by  the  third  visceral  arch,  and 
behind  by  the  fourth.  Note  the  number  of  mesoblastic  somites  and 
the  condition  of  the  mesoblastic  segmental  plates. 

Note  how  far  back  the  foregut  is  closed.  Locate  the  head  fold  of 
the  amnion,  and  note  how  far  back  it  is  closed.  Note  changes  that 
have  taken  place  in  the  vascular  area.  In  studying  the  sections  it 
will  be  found  that  a  section  cut  transversely  to  the  trunk  will  pass 
horizontally  through  the  forebrain  and  through  the  midbrain. 

Study  a  section  through  the  trunk  a  short  distance  behind  the 
heart.  Observe  the  elevation  of  the  axis  of  the  body.  Note  the 


OUTLINE   FOR   LABORATORY   STUDY   OF   THE   CHICK        335 

way  in  which  the  lateral  folds,  or  the  lateral  limiting  sulci,  in  the 
somatopleure,  delimit  the  embryonic  from  the  extra-embryonic  area. 

Note  the  appearance  of  the  mesenchyme,  the  approximation- oi 
the  two  dorsal  aortae,  the  appearance  of  the  amniotic  folds.  Ob- 
serve in  the  mesoderm  the  posterior  cardiac  veins,  and  the  myo- 
tomes,  or  muscle  plates.  The  sclerotome  is  made  up  of  the  mass  of 
mesenchyme  between  the  myotome,  on  the  one  hand,  and  the 
neural  tube  and  the  notochord,  on  the  other.  Note  the  folding 
of  the  splanchno-pleure,  and  note  if  there  is  present  the  Wolffian 
duct,  or  the  nephrotome. 

Study  sections  through  the  optic  vesicles.  Note  if  there  is  the 
beginning  of  the  lens.  Do  you  note  the  diverticula  of  the  pharynx? 
Can  you  identify  the  closed  amnion  and  the  chorion? 

Study  sections  through  the  auditory  pit.  Note  fusion  of  the  gill 
pouches  with  the  ectoderm.  Note  the  blood-vessels.  Study  sec- 
tions through  the  region  of  the  heart,  through  the  roots  of  the  vitel- 
line  veins,  and  through  the  primitive  streak,  if  it  is  still  present. 

For  this  study  it  will  appear  that  the  anterior  end  has  developed 
in  advance  of  the  posterior  end.  The  tail  fold  has  probably  just 
begun. 

Write  a  description  of  the  pharynx,  and  of  the  circulation  at  this 
stage. 

4.  THE  EMBRYO  SLXTY-EIGHT  TO  SEVENTY-TWO  HOURS  OLD  WITH 
CERVICAL  FLEXURES  FORMED. 

In  a  study  of  the  living  embryo  note  the  changes  visible  to  the 
naked  eye  since  forty-eight  hours  old.  Note  the  difference  in  the 
blood-vessels  of  the  vascular  area.  Name  the  arteries  and  veins. 
Note  the  beating  of  the  heart. 

In  a  study  of  the  entire  mount  note  that  a  second,  the  cervical 
flexure,  has  appeared  in  the  head.  Note  that  the  tail  fold  is  well 
formed.  Note  the  position  of  the  embryo  on  the  blastoderm.  De- 
termine if  the  amnion  is  completely  closed.  Note  the  olfactory 
pits  on  the  ventral  surface  of  the  head,  a  short  distance  in  front  of  the 
optic  stalks.  Note  the  telencephalon,  a  rudiment  of  the  cerebral 
hemispheres  and  an  extension  of  the  primary  forebrain.  It  is 
bilobed  anteriorly.  The  optic  stalks  are  attached  to  the  floor  near 
the  anterior  end  of  the  thalamencephalon.  Note  the  infundibular 
region,  which  is  the  depressed  region  behind  the  optic  stalks.  In 
the  roof  of  the  thalamencephalon  there  is  a  short  diver ticulum,  the 
epiphysis.  The  mesencephalon,  or  midbrain,  forms  the  apex  of 


336  ANATOMY   OF   THE   DOMESTIC   FOWL 

the  cranial  flexure,  and  is  united  to  the  hindbrain  by  a  narrow 
isthmus.  The  metencephalon,  or  rudimentary  cerebellum,  appears 
as  a  thick  portion  on  the  most  anterior  division  of  the  hindbrain. 
The  rest  of  the  hindbrain  is  provided  with  a  transparent  roof  and 
constitutes  the  myelencephalon,  or  the  rudimentary  medulla  ob- 
longata.  Observe  the  inner  and  the  outer  wall  of  the  optic  cup,  the 
lens,  the  choroid  fissure,  and  the  posterior,  or  vitreous,  chamber. 

Note  the  form  of  the  otocyst,  or  auditory  sac.  Note  above  which 
visceral  arch  it  lies.  Note  the  number  of  visceral  clefts.  The 
visceral  arches  are  formed  by  the  thickening  of  the  walls  of  the 
bounding  clefts.  The  visceral  arches  are  as  follows:  the  first  is 
the  mandibular,  or  hyomandibular,  arch,  which  is  in  front  of  the 
first  cleft.  From  this  there  is  developed  the  lower  jaw.  Note  if 
there  is  a  maxillary  process  arising  from  the  dorsal  angle  of  the 
arch.  The  second  arch  is  the  hyoid  arch,  which  is  located  behind 
the  first  cleft.  Then  follow  in  order  the  third,  the  fourth,  and  the 
fifth  visceral  arches.  Note  above  the  mandibular  arch  the  rudi- 
mentary trigeminal  ganglion,  and  above  the  hyoid  arch  the  rudi- 
mentary acoustico-facialis.  The  latter  is  in  contact  with  the  anterior 
walls  of  the  auditory  sac.  The  rudimentary  glossopharyngeal 
ganglion  is  noted  above  the  third  visceral  arch.  The  vagus,  or 
pneumogastric,  ganglion  is  located  above  the  fourth  and  the  fifth. 
Note  the  form  and  the  postion  of  the  heart.  Note  the  anterior  and 
the  posterior  limb  rudiment  in  the  trunk. 

In  a  study  of  the  sections  it  is  found  that  cuts  transverse  to  the 
trunk  pass  about  horizontally  through  the  forebrain.  At  this  age 
the  following  sections  of  the  embryo  should  be  studied: 

First,  through  the  hindbrain,  at  which  level  will  be  noted  the 
auditory  sacs,  the  neuromeres,  the  trigeminal,  the  acoustico-facialis, 
and  the  glossopharyngeal  and  the  vagus  ganglion. 

Second,  through  the  upper  part  of  the  pharynx,  at  which  level 
will  be  observed  the  midbrain,  the  hindbrain,  the  visceral  pouches, 
the  nerves,  and  the  blood-vessels.  ' 

Third,  through  the  choroid  fissure  of  the  optic  cups.  Note  the 
parts  of  the  eye,  and,  on  the  other  side  of  the  section,  the  heart. 

Fourth,  a  study  of  a  section  through  the  olfactory  pits. 

Fifth,  a  study  of  a  section  through  the  pancreatic  and  the  hepatic 
dverticula. 

Sixth,  a  study  at  the  beginning  of  the  allantois  through  the  hind- 
gut. 


OUTLINE  FOR  LABORATORY  STUDY  OF  THE  CHICK    337 

At  this  age  it  is  of  interest  to  study  the  systems  of  organs.  Ob- 
serve the  manner  in  which  the  splanchno-pleure  folds  to  form  the 
walls  of  the  intestine.  Note  the  commencement  of  the  mesentery. 
Note  that  the  foremost  part  of  the  alimentary  tract  is  formed  from  the 
stomodeal  invagination  of  the  ectoderm.  The  hypophysis  is  formed 
from  a  dorsal  outgrowth  of  this.  Note  its  relation  to  the  brain. 

The  following  structures  are  formed  from  outgrowths  of  the 
ectoderm  at  this  stage: 

First,  the  visceral  pouches. 

Second,  the  median  rudiment  of  the  thyroid.  This  is  an  out- 
growth from  the  pharynx  between  the  two  hyoid  arches. 

Third,  the  rudimentary  lungs,  which  develop  in  a  pair  from  a 
median  ventral  diverticulum  of  the  alimentary  tract,  just  behind  the 
last  visceral  pouch.  The  esophagus  is  just  posterior  to  this.  The 
esophagus,  very  short  at  this  stage,  is  continuous  with  a  slightly 
wider  part  that  develops  into  the  stomach. 

Fourth,  the  first  liver  diverticulum,  and,  at  a  short  distance 
posterior  to  this,  the  second  liver  diverticulum. 

Fifth,  the  pancreas  is  at  a  point  where  the  intestine  opens  ven- 
trally.  It  first  appears  as  a  slight  thickening  of  the  dorsal  angle  of 
the  intestine. 

Sixth,  the  ventral  wall  of  the  hind-gut  forms  a  wide  evagination. 

Seventh,  the  beginning  of  the  allantois. 

After  the  whole  series  of  transverse  sections  have  been  studied  and 
drawn,  construct  a  longitudinal  section  of  the  fetus,  including  a 
reconstruction  of  the  alimentary  tract. 

At  this  stage  the  heart  is  a  simple  tube.  The  following  divisions 
are  distinctly  visible:  the  auricular  portion,  the  ventricular  portion, 
the  sinus  venosus,  and  the  bulbus  arteriosus.  The  union  of  the  two 
ductus  Cuvieri  and  the  ductus  venosus  form  the  sinus  venosus.  The 
two  ductus  Cuvieri  are  formed  by  the  union  of  the  anterior  and  the 
posterior  cardinal  veins.  The  ductus  venosus  is  formed  by  the 
union  of  the  small  right  and  the  large  left  vitelline  vein.  These 
latter  veins  return  the  blood  from  the  yolk  sac.  The  sinus  venosus 
empties  into  the  single  auricle  above  which  it  is  located.  The 
single  auricle  is  later  divided  into  two  chambers,  the  right  and  the 
left  auricle.  At  this  stage  it  is  widest  in  the  lateral  direction. 
The  auricle  empties  directly  into  the  ventricle.  The  ventricle  lies 
ventrally  and  behind  the  auricle.  This  location  is  due  to  the  bend- 
ing of  the  heart  at  this  stage  of  development.  Its  hindmost  portion 

22 


338  ANATOMY   OF   THE   DOMESTIC   FOWL 

forms  the  future  apex  of  the  heart.  If  the  series  of  sections  be 
studied  from  the  posterior  forward,  the  ventricle  will  be  first  to 
appear  in  the  sections.  Just  beneath  the  auricular  portion  of  the 
heart  there  is  the  bulbus  arteriosus.  The  bulbus  arteriosus  soon 
divides  into  a  number  of  aortic  arches.  There  is  an  ascending  pair  in 
each  of  the  visceral  arches.  The  dorsal  aorta  is  formed  by  the  union 
of  the  aortic  arches  above  the  visceral  arches.  The  aortic  arches  are 
first  continued  a  short  distance  forward  as  the  carotid  arteries.  The 
dorsal,  or  posterior,  aorta  passes  backward  under  the  notochord. 
The  dorsal  aorta  divides  into  two  parallel  aortae  which  give  off  on 
each  side  the  vitelline  arteries.  Note  other  branches  of  this  aorta. 

The  veins  at  this  stage  consist  of  the  anterior  and  posterior  cardi- 
nal, the  ductus  venosus,  the  ductus  Cuvieri,  and  the  vitelline  veins. 

Make  drawing  of  the  circulatory  system  after  a  completion  of  the 
study  of  the  series  of  sections. 

Make  a  study  of  the  nervous  system  according  to  hints  already 
given. 

The  dorsal  and  the  ventral  roots  of  the  spinal  nerves  are  given  off 
separately,  and  secondarily  unite.  From  the  neuroblasts  of  the  cord 
there  are  at  regular  intervals  outgrowths  representing  the  ventral 
roots.  From  the  neural  crest  there  develop  segmental  collections 
of  neuroblasts  which  form  the  spinal  ganglia,  from  which  the  dorsal 
spinal  nerve  roots  develop.  In  fact  this  developmental  stage  can 
be  observed  in  embryos  only  forty-eight  hours  old,  first  appearing 
as  a  line  of  cells  springing  on  each  side  from  the  angle  between 
the  neural  canal  tube  and  the  external  epiblast.  In  the  section 
from  the  embryo  seventy-two  hours  old  there  are  observed  the 
rudiments  of  the  development  of  these  spinal  nerves.  Four  pri- 
mary ganglia  develop  in  the  neural  crest  of  the  head.  These 
ganglia  are  as  follows:  the  acoustico-facialis  ganglia,  which  is  located 
over  the  hyoid  arch;  the  ganglia  of  the  trigeminus,  which  is  located 
over  the  mandibular  arch;  the  ganglia  of  the  glosso-pharyngeus, 
which  is  located  over  the  third  visceral  arch;  and  the  ganglia  of  the 
vagus,  which  is  located  over  the  third  and  the  fourth  visceral  cleft. 

In  this  stage  of  development  the  trigeminal  and  the  acoustico- 
facialis  are  clearly  visible. 

On  each  side  and  dorsal  to  the  aorta  is  noted  the  Wolffian  body, 
or  mesonephros.  The  Wolffian  body  (Fig.  82  -E)  consists  of  a 
series  of  tubules  imbedded  in  the  mesenchyme.  The  openings  into 
the  Wolffian  duct  lie  just  beneath  the  cardinal  vein. 


OUTLINE   FOR  LABORATORY   STUDY   OF   THE   CHICK        339 

In  a  study  of  the  Wolffian  duct  determine  just  how  far  anteriorly 
and  how  far  posteriorly  it  extends.  Note  whether  it  empties  into 
the  cloaca. 

Each  tube  beginning  in  a  blind  extremity  is  later  dilated.  It  has 
a  thin  wall,  and  is  situated  near  the  median  portion  of  the  Wolffian 
body.  The  tubule  proper  passing  transversely,  opens  into  the  duct. 
The  upper  wall  of  the  thin-walled  part  is  invaginated  by  a  mass  of 
mesenchyme  that  receives  a  small  vessel  from  the  dorsal  aorta.  The 
Malpighian  corpuscle,  consisting  of  a  glomerule  and  Bowman's  cap- 
sule, is  thus  established.  In  the  study  of  the  four  days  old  chick 
note  the  further  development  of  these  parts. 

In  a  study  of  a  chick  four  days,  or  ninety-six  hours  old,  note  to 
what  extent  the  yolk  is  covered  by  the  blastoderm.  It  will  be  noted 
that  the  embryo  lies  in  the  extra-embryonic  cavity.  This  cavity  is 
bounded  above  by  the  chorion  and  below  by  the  splanchnopleure. 
In  removing  the  amnion  from  the  embryo,  note  the  relation  to  the 
somatic  umbilicus.  Note  the  relation  of  the  splanchnic  umbilicus 
to  the  splanchno-pleure.  What  relation  has  the  allantois  to  the 
above? 

In  examining  the  head,  locate  the  cerebral  hemispheres,  and  note 
their  development.  Locate  the  pineal  gland.  Note  changes  in  the 
olfactory  pit  and  the  eye.  Locate  the  lens  and  the  choroid  fissure. 
Note  that  the  maxillary  process  of  the  mandibular  arch  lies  beneath 
the  eye  and  behind  the  olfactory  pits.  Note  the  otocyst  and  the 
relations  of  the  other  arches  to  the  above  structures. 

In  a  study  of  the  trunk,  note  the  tail,  the  allantois,  Wolffian 
ridges,  the  heart,  and  the  condition  and  the  position  of  the  rudi- 
mentary limbs. 

Make  drawing  of  embryo  from  the  side  view.  Carefully  cut  off 
the  head  immediately  behind  the  last  visceral  arch,  and  study  and 
draw  the  structures  observed  on  the  ventral  side.  Note  the  maxil- 
lary processes,  the  mandibular  and  the  hyoid  arch,  the  nasal  pits, 
and  the  fronto-nasal  process,  which  is  just  beginning  its  development. 

In  a  study  of  transverse  sections  observe  from  your  drawing  at 
what  level  the  section  is  made.  Study  and  draw  a  section  made 
through  the  region  of  the  anterior  limbs.  Note  the  spinal  ganglion, 
the  muscle  plate,  or  myotome,  the  condensation  of  mesenchyme 
around  the  notochord,  the  pancreas,  the  liver,  and  the  intestine; 
and  note  the  distribution  of  the  mesenchyme.  Note  the  ventral 
roots  of  the  spinal  nerves,  and  the  neuroblasts  in  the  spinal  cord. 


34°  ANATOMY   OF   THE   DOMESTIC   FOWL 

In  sectioning  the  embryo  from  before  backward,  the  first  sections 
will  pass  horizontally  through  the  hindbrain  and  the  midbrain 
region.  Note  the  parts,  including  the  auditory  vesicle.  In  the 
first  series  of  sections  also  locate  the  ganglia  of  the  pneumogastric, 
or  vagus,  the  acoustico-facialis,  the  trigeminus,  and  the  glosso- 
pharyngeal  nerves.  Note  the  notochord  and  the  cardinal  veins. 
After  the  disappearance  of  the  ear,  we  observe  the  midbrain,  which, 
is  located  at  one  end  of  the  section,  and  the  cord  at  the  other  end. 
The  region  between  lies  just  above  the  pharynx.  In  the  following 
series  study  the  visceral  arches.  Note  the  third  pair  of  cranial,  or 
motor  ocular,  nerves.  This  latter  nerve  springs  from  the  floor  of 
the  midbrain.  From  the  ventral  prolongation  of  the  floor  of  the 
thalamencephalon  there  arises  the  infundibulum.  The  hypophysis 
is  located  just  beneath  the  infundibulum.  At  this  stage  the  hypo- 
physis appears  as  a  tube  to  empty  into  the  mouth.  This  is  an  in- 
growth of  the  oral  epithelium. 

In  a  study  of  a  section  through  the  center  of  the  eye  we  should 
observe  the  lens  and  optic  stalk.  This  is  in  the  region  of  the  optic 
chiasm.  Note  the  choroid  fissure  and  the  pineal  gland,  the  latter 
appearing  just  beyond  the  eyes.  Just  forward  lies  the  telencephalon, 
or  rudiments  of  the  cerebral  hemispheres. 

In  a  study  of  the  alimentary  tract  we  note  that  the  mouth  is 
bounded  by  the  mandibular  arches.  Note  the  maxillary  processes, 
and  the  ventral  surface  of  the  head.  A  finger-like  diverticulum, 
extending  from  the  roof  of  the  ruptured  double  membrane,  formerly 
separating  the  pharynx  from  the  arches,  forms  the  hypophysis. 
The  great  development  of  the  visceral  pouches  makes  the  pharynx 
rather  complex.  In  studying  sections  horizontally  through  the 
pharyngeal  region  note  the  various  visceral  arches  and  pouches. 
Note  the  arteries  of  the  thyroid  diverticulum. 

In  the  series  note  the  changed  development  of  the  lung  rudiments, 
the  glottis,  the  esophagus,  the  trachea,  and  the  bronchi.  The  bron- 
chi appear  in  pairs.  Note  that  the  liver  has  assumed  proportions, 
and  that  it  surrounds  the  common  trunk  of  the  vitelline  veins, 
which  it  divides  into  two  parts.  The  sinus  venosus  lies  close  to  the 
heart.  The  ductus  venosus  is  also  surrounded  by  the  liver.  Above 
the  "tip  of  the  ventricle  we  note  a  dilatation  which  represents  the 
stomach.  The  hepatic,  or  bile  duct  is  located  immediately  behind 
the  stomach.  This  duct  is  formed  by  the  fusion  of  the  right  and  the 
left  duct.  Locate,  draw,  and  describe  the  pancreas;  trace  the  intes- 


OUTLINE    FOR   LABORATORY    STUDY    OF    THE    CHICK         341 

tine;  locate  the  splanchnic  umbilicus,  or  yolk  stalk;  locate  the  allan- 
tois  stalk,  and  trace  its  connection  with  the  hind-gut. 

In  the  series,  locate  and  study  the  Wolffian  ducts,  the  beginning 
of  the  Miillerian  duct,  the  embryonic  kidney,  or  mesonephros,  the 
permanent  kidney,  or  metanephros.  The  urino-genital  ridge  is 
made  up  of  all  the  above  except  the  last  named.  The  urino-genital 
ridge  forms  a  rounded  projection  on  each  side  of  the  mesentery  into 
the  dorsal  angles  of  the  body  cavity. 

The  Wolffian  ducts  empty  into  the  cloaca.  There  are  two  ducts 
which  may  be  traced  far  forward,  and  which  are  found  to  extend 
backward  along  the  lateral  margin  of  the  ridge  to  the  cloaca.  Along 
the  greater  part  of  their  length  we  note  tubules  emptying  into  them. 

Beginning  near  the  anterior  end  of  the  urinogenital  ridge,  we  note 
that  the  Miillerian  ducts  arise  from  a  thickened  line  of  epithelium. 
The  greater  part  of  the  ridge  is  formed  by  the  mesonephros.  This  is 
made  up  of  a  series  of  tubules  in  each  of  which  we  may  distinguish 
two  parts  as  follows :  a  tuft  of  capillaries  from  the  aorta  forming  the 
glomerules,  surrounded  by  a  thin  walled  invaginated  capsule,  mak- 
ing up  the  Malpighian  corpuscle;  and  the  tubules  proper.  The 
tubules  lead  from  the  corpuscles,  or  glomerules,  to  the  Wolffian  duct. 

The  germinal  epithelium  constitutes  the  essential  portions  of  the 
gonad,  or  ovary,  or  testis.  The  germinal  epithelium  arises  from  a 
thickening  of  the  peritoneum  of  the  median  wall  of  the  ridge.  The 
gonad  is  found  near  the  anterior  end  of  the  ridge.  At  about  this 
age  of  the  embryo  there  should  appear  the  primitive  ovary  or  testis. 
Near  the  posterior  termination  of  the  Wolffian  duct  and  from  the 
dorsal  diverticulum  there  arises  the  ureter,  or  metanephros  duct. 

In  these  series  there  should  be  studied  the  heart  and  circulation, 
which  will  be  found  similar  to  the  sections  from  the  embryo  seventy- 
two  hours  old. 

Work  out  a  summary  of  the  relations  of  the  allantois  and  the 
yolk  stalk  to  the  intestines;  the  relations  of  the  Wolffian  ducts  to  the 
intestines;  the  origin  of  the  ureters  from  the  Wolffian  ducts;  the 
relations  of  the  lungs,  the  liver,  and  the  thyroid  gland;  the  relations 
of  the  blood-vessels;  a  study  of  the  muscle  plates;  the  relations  of 
epiphysis,  hypophysis,  infundibulum,  mouth,  and  pharynx;  the 
relations  of  the  vagus,  or  pneumogastric,  trifacial,  acoustico-facialis, 
and  glossopharyngeal  nerves  to  the  visceral  arches. 

In  addition  to  the  study  of  embryos  at  the  end  of  each  of  the 
first  four  days  of  incubation,  a  study  should  be  made  of  preserved 


34 2  ANATOMY   OF   THE   DOMESTIC  FOWL 

museum  specimens  each  of  which  represents  the  development  of  a 
day  up  to  and  including  the  twenty-first  day. 

THE  DERIVATIVES  OF  THE  GERM-LAYERS 

From  the  three  primary  germ-layers  are  developed  the  various 
tissues  and  organs  of  the  body  by  metamorphoses  which  may  be 
referred  to  the  two  fundamental  processes  of  specialization,  or  the 
adaptation  of  structure  to  function,  and  of  unequal  growth,  which 
latter  results  in  the  formation  of  folds,  ridges,  and  constrictions. 

From  the  ectoderm  are  produced: 

The  epidermis  and  its  appendages,  including  the  nails,  the  epi- 
thelium in  connection  to  the  feathers  and  the  feathers. 

The  infoldings  of  the  epidermis,  including  the  epithelium  of  the 
mouth,  epithelium  of  the  salivary  glands  and  the  anterior  lobe  of  the 
pituitary  body,  or  hypophysis. 

The  epithelium  of  the  nasal  tract  with  its  glands  and  communicat- 
ing cavities. 

The  epithelium  lining  the  external  auditory  canal,  including  the 
outer  stratum  of  the  membrana  tympani. 

The  lining  of  the  anus. 

The  epithelium  of  the  conjunctiva  and  of  the  anterior  part  of  the 
cornea,  the  crystalline  lens. 

The  spinal  cord,  the  brain  with  its  outgrowths,  including  the 
optic  nerve,  the  retina,  and  the  posterior  lobe  of  the  pituitary  body. 

The  epithelium  of  the  inner  ear. 

From  the  entoderm  are  produced : 

The  epithelium  of  the  respiratory  tract. 

The  epithelium  of  the  digestive  tract,  from  the  back  part  of  the 
pharynx  to  the  anus,  including  its  associated  glands,  the  liver,  and 
the  pancreas. 

The  epithelial  parts  of  the  middle  ear  and  of  the  eustachian  tube. 

The  epithelium  of  the  thymus  and  the  thyroid  bodies. 

From  the  mesoderm  are  developed: 

Connective  tissue  in  all  its  modified  forms,  such  as  bone,  cartilage, 
Jymph,  blood,  fibrous  and  areolar  tissue. 

Muscle  tissue. 

All  endothelial  cells,  as  of  joint-cavities,  bursal  sacs,  lymph 
sacs,  blood-vessels,  pericardium,  and  endocardium,  pleura,  and 
peritoneum. 

The  spleen. 


OUTLINE   FOR   LABORATORY   STUDY   OF   THE   CHICK        343 

The  kidneys  and  ureters. 

The  testicles  and  the  system  of  excretory  ducts. 

The  ovary  and  oviduct. 

PREPARATION  OF  STRUCTURES  FOR  STUDY 

It  is  hoped  that  the  following  suggestions  will  be  helpful  in  the 
laboratory  work. 

Directions  for  Dissecting  Muscles. — The  muscles  that  are  brought 
into  great  play  in  movements  of  the  bird's  limbs  are  dark  carmine 
in  color,  while  those  which  are  not  brought  greatly  into  use  are  pale 
or  white  in  color. 

The  tendons  are  made  up  of  white  fibrous  connective  tissue,  are 
very  dense,  and  pearly  white  in  color. 

In  securing  a  bird  for  dissection  of  muscles  it  is  best  to  select  one 
in  rather  poor  flesh,  as  the  fat  is  annoying.  The  bird  may  be 
chloroformed  or  killed  in  a  bell  jar  by  aid  of  illuminating  gas. 
After  the  bird  is  dead  pluck  all  the  feathers  and  immerse  it  in  a  10 
per  cent,  solution  of  formaldehyde  or  of  80  per  cent,  alcohol.  It  is 
best  to  puncture  the  abdominal  wall  so  that  the  fluid  may  at  once 
fill  the  abdominal  cavity  and  more  readily  gain  access  to  the  chest 
cavity;  and  to  puncture  the  skin  at  various  points  so  that  the  liquid 
may  more  quickly  become  disseminated  among  the  muscular  struc- 
tures. Post-mortem  changes  quickly  take  place  if  these  precautions 
are  not  taken.  The  liquid  surrounding  the  carcass  should  be  at 
least  twice  the  quantity  of  the  bulk  of  the  carcass. 

The  first  dissection  should  be  to  lay  bare  the  dermal  muscles. 
The  dermal  muscles  are  of  two  kinds,  true  dermal  and  dermo-osse- 
ous.  The  dermal  muscles  have  their  origin  and  insertion  in  the  skin, 
and  control  the  movements  of  the  different  groups  of  feathers.  The 
dermo-osseous  have  their  origin  on  some  part  of  the  skeleton,  and 
insert  to  the  integuments. 

The  cfermal  muscles  vary  with  the  characteristics  of  the  bird,  we 
do  not  find  all  the  known  dermal  muscles  in  any  one  specimen.  A 
cock  of  the  Cornish  breed  will  show  these  muscles  best  developed. 
Birds  possess  an  enormous  system  of  minute  muscles  divided  up  into 
an  infinite  number  of  fasciculi,  to  act  harmoniously  upon  the  feather 
quills  and  to  agitate  collectively  the  plumage.  By  the  aid  of  a  low- 
power  lens  the  action  of  the  feather  muscles  in  the  large  quill-butts 
of  the  wing  or  the  tail  may  be  studied. 

The  muscles  may  be  studied  in  groups  as  outlined  in  the  text. 


.* 


344  ANATOMY   OF    THE   DOMESTIC   FOWL 

Make  an  incision  through  the  skin  down  to  the  bone  on  the  superior 
part  of  the  head,  parallel  and  close  to  the  base  of  the  upper  mandible, 
and  extending  completely  across.  From  the  outer  end  of  this  make 
an  incision  backward  and  down  to  the  skull  and  posteriorly.  The 
muscles  of  the  upper  part  of  the  neck  will  then  be  exposed.  The 
straight  incision  should  extend  to  about  a  half  inch  on  the  inside  of 
the  upper  eyelid  of  the  same  side.  Reflect  the  flap  of  skin  from  the 
top  of  the  skull,  and  carefully  examine  the  under  side  of  it  in  the 
median  line,  where  it  overlies  the  frontal  region.  The  dermo-fron- 
talis  will  be  observed  if  it  be  present.  In  many  birds,  especially  in 
females,  it  may  not  be  discernible,  and  may  be  considered  absent. 
To  expose  the  circumconcha^make  an  incision  completely  around 
the  ear;  then  carefully  dissect  to  the  ear  base.  A  dermal  circular 
muscle  should  be  observed.  To  expose  the  dermo-temporalis 
extend  the  longitudinal  incision  down  the  back  of  the  neck  to  a 
point  between  the  clavicular  heads,  carrying  it  just  through  the 
skin  and  about  one-fourth  of  an  inch  to  the  side  of  the  median  line. 
Remove  the  skin  from  the  throat  and  the  anterior  portion  of  the 
chest.  Lay  open  the  alar  and  parapatagial  duplicatures  of  the  skin. 
This  exposes  a  number  of  dermal  muscles.  The  dermo-temporalis 
is  now  observed  to  extend  from  a  small  depression  just  above  and 
anterior  to  the  temporal  fossa.  It  makes  slight  attachments  to  the 
temporal  muscle,  which  it  covers,  and  extends  backward  as  a  thin 
ribbon-shaped  muscle,  the  fibers  blending  with  those  of  the  cleido- 
trachealis,  and  becomes  lost  upon  trie  skin  in  front  and  opposite  the 
shoulder-joint.  At  times  its  fibers  blend  with  those  of  the  dermo- 
tensor  patagii. 

As  the  musculature  of  the  fowl  is  loosly  arranged,  the  rest  of  the 
dissection  is  easily  done  if  care  be  exercised. 

The  ligaments  may  be  dissected  after  the  completion  of  the  study 
of  muscles,  using  the  same  subject  or,  a  two  pound  broiler  be  pre- 
pared by  killing  in  the  gas  chamber,  plucking  the  feathers  and 
parboiling  just  till  the  flesh  becomes  tender  and  is  easily  removed, 
it  will  be  observed  that  all  structures  can  be  removed  from  the 
points  exposing  the  ligaments  distinctly.  The  ligaments  appear 
swollen  and  more  easily  observed  for  study. 

Directions  for  the  Study  of  the  Viscera. — Carefully  remove  the 
right  and  the  left  abdominal  and  thoracic  walls,  allowing  a  strip 
of  tissue  to  remain  in  the  median  line  to  hold  the  organs  in  their 
normal  position.  To  open  these  cavities  it  is  necessary  to  use  the 


OUTLINE    FOR  LABORATORY    STUDY    OF    THE    CHICK         345 

bone  saw  and  the  scalpel.  The  organs  may  now  be  studied  from 
each  side.  To  make  a  longitudinal  section  through  the  median  line, 
select  a  small  bird,  one  weighing  not  more  than  2  pounds,~kill, 
and  preserve  in  a  10  per  cent,  solution  of  formaldehyde  for  three 
days.  Then  with  a  sharp,  thin,  long-bladed  knife  make  an  incision 
at  one  sweep  through  the  median  line  of  the  body  down  to  the  back 
bone,  and  with  the  bone  saw  section  through  the  vertebrae.  If  it  is 
difficult  to  cut  through  the  breast-bone,  saw  through  before  making 
the  incision.  In  small  birds  the  entire  cut  may  be  made  without 
the  aid  of  the  saw. 

Directions  for  the  Study  of  Arteries/ — Arteries  should  be  injected. 
Veins  are  usually  more  or  less  filled  with  blood  so  that  the  tracing  of 
these  is  not1  so  difficult  as  the  tracing  of  uninjected  arteries.  Nerves 
are  white  and  no  difficulty  is  usually  encountered  in  tracing  them. 

The  courses  of  arteries,  veins,  and  nerves  are  side  by  side,  and 
many  of  them,  as  in  mammals,  are  arranged  in  the  order  of  veins, 
arteries,  nerves,  the  veins  being  in  front. 

The  injection  apparatus  consists  of  the  following  parts:  air-com- 
pression chamber,  to  which  is  attached  a  pressure  pump.  A  mano- 
meter made  of  glass  tubing  6  millmeters  in  diameter,  inside  measure- 
ment. This  tube  is  partly  filled  with  mercury,  and  a  scale  in  centi- 
meters is  made  from  the  top  of  the  right-hand  tube  (Fig.  84,  No.  8). 
This  ruling,  or  gauge,  should  be  about  15  centimeters  long.  Extend- 
ing from  the  right  extremity  of  the  U-tube  is  a  small  rubber  tubing 
which  is  attached  to  the  chamber  containing  the  injection  fluid; 
and  extending  from  the  inferior  part  of  this  chamber  is  another  tub- 
ing which  has  the  injection  needle  attached  to  the  free  end. 

The  injection  should  be  done  under  120  millimeters  pressure. 
The  stop  cock  of  the  pressure  chamber  is  released  sufficiently  to 
raise  the  mercury  in  the  U-tube  six  centimeters,  which  multiplied 
by  2,  the  amount  of  work  required  to  raise  two  columns,  makes  120 
millimeters  pressure.  If  this  pressure  be  maintained,  all  vessels 
should  be  injected  without  rupture.  The  same  process  may  be  used 
in  injecting  the  air  cells  through  the  trachea. 

The  injecting  material  may  consist  of  one  part  finely  sifted  plaster 
of  Paris,  four  parts  water,  and  sufficient  gentian  violet  to  make  a 
violet  color.  For  the  coloring,  red  aniline  may  be  used  in  preparing 
this  material.  The  dye  should  be  dissolved  in  the  water  to  be  used 
in  making  the  injection  liquid.  Caution  must  be  used  and  the 
work  rapidly  done,  as  the  plaster  soon  sets,  or  becomes  solid,  in  the 


346  ANATOMY   OF   THE  DOMESTIC  FOWL 

needle  or  in  the  tubing.  A  small  cannula  should  be  used,  since 
the  endothelial  lining  of  the  arteries  are  easily  injured  and  diffi- 
culty may  thus  be  created. 

Select  for  arterial  dissection  an  old  cock,  as  in  a  bird  of  this  kind 
the  arteries  are  larger  and  the  difficulties  are  reduced.  Select  for 
bleeding  and  injection  the  ischiadic  artery  in  the  thigh  region.  With 
the  sharp  point  of  the  thin  blade  of  a  knife  make  an  incision  length- 
wise of  the  artery  being  careful  not  to  strip  back  the  endothelial 
lining  of  the  artery.  Allow  as  much  of  the  blood  as  will  escape 
before  injecting;  in  fact,  the  arteries  should  be  thoroughly  emptied, 
so  that  there  is  no  longer  danger  of  a  clot's  plugging  some  vessel 
and  thus  preventing  its  filling:  Since  the  blood  of  most  birds  coagu- 
lates in  about  thirty  seconds,  this  work  must  be  done  rapidly,  care 
being  exercised  to  keep  the  flow  running  as  long  as  possible.  After 
bleeding  is  completed,  insert  the  cannula  and  tie  the  vessel  tightly 
around  the  cannula  to  prevent  the  escape  of  the  injecting  fluid.  See 
that  all  connections  are  sufficiently  tight  to  prevent  the  escape  of 
liquid  under  pressure.  After  the  injection  is  completed,  remove  the 
cannula  and  tie  the  artery  with  a  small  twine,  preferably  cotton. 
Quickly  remove  all  injecting  fluid  from  the  needle,  the  tubing,  and  the 
injecting  chamber. 

During  the  operation  of  bleeding  the  cock  may  be  chloroformed, 
care  being  taken  not  to  administer  chloroform  to  kill  him;  for  it  is 
necessary  to  maintain  life  as  long  as  possible  so  that  the  heart  may 
be  kept  beating  and  all  blood  possible  drained  from  the  arteries. 
After  the  injection  is  completed  the  bird  may  be  plucked  and  im- 
mersed in  the  preservative  fluid  in  the  same  manner  as  in  the 
preparation  for  dissection  for  muscles. 

The  arteries,  the  veins,  and  the  nerves  may  now  be  dissected  and 
studied  in  relation  to  one  another  and  in  relation  to  the  muscles, 
the  bones,  and  other  structures.  The  skin  should  not  be  removed 
from  the  shanks  till  it  is  desired  to  dissect  these  parts,  as  the  tissues 
quickly  dry  out.  In  fact,  the  tendons  of  the  shanks  and  toes  can 
best  be  dissected  while  the  specimen  is  fresh. 

A  Study  of  the  Structure  of  Bones. — Longitudinal  and  transverse 
sections  of  old  bone  may  be  made  by  making  thin  longitudinal  and 
transverse  sections  with  the  bone  saw,  and  then  by  making  them 
very  thin  with  a  fine  three-cornered  file.  Examining  under  the 
low  power  microscope,  we  note  the  lacunae,  the  canaliculi,  and  the 
Haversian  system. 


OUTLINE  FOR  LABORATORY  STUDY  OF  THE  CHICK   347 

Similar  sections  in  green  bone  may  be  studied  if  prepared  as 
follows.  Secure  specimen  of  bone  just  removed  from  a  fowl  and 
place  it  for  three  days  in  a  10  per  cent,  aqueous  solution  of  hydro- 
chloric acid.  Test  by  puncturing  with  a  needle,  and,  if  all  the 
mineral  salts  are  removed,  place  in  a  water  bath  and  wash  for  four 
hours.  Pass  it  through  the  fluids  usually  employed  in  preparing 
specimens  for  sectioning  with  the  microtome.  Stain  as  sections  of 
other  tissue  for  microscopic  study.  See  the  description  below.  If 
the  ends  of  the  bone  be  included,  it  will  enable  the  student  to  study 
not  only  compact  bone  but  also  cancellated  bone  and  articular,  or 
hyaline  cartilage,  and  in  some  of  the  bones,  as  the  femur,  the  red 
marrow.  , 

Special  Technic  for  the  Dissection  of  Cranial  and  Spinal  Nerves. — 
It  is  rather  difficult  to  dissect  the  cranial  and  spinal  nerves  of  the 
fowl,  owing  to  the  fact  that  the  structures  are  very  small.  The 
bone  is  rather  hard  and  the  nerve  tissue  so  delicate  that  great  skill 
must  be  attained  to  achieve  any  degree  of  success. 

A  simple  technic  has  been  developed  as  follows :  Place  the  head 
and  neck,  or  other  structures  of  the  spinal  column  in  a  10  per  cent, 
aqueous  solution  of  hydrochloric  acid  for  three  or  more  days,  the 
time  depending  on  the  size  of  the  specimen  and  the  amount  of  soft 
structures  surrounding  it.  This  solution  removes  all  the  calcium 
salts  from  the  bone  and  makes  the  removal  of  the  bony  structures 
a  less  difficult  task. 

Directions  for  the  Study  of  Soft  Structures. — Secure  a  specimen  of 
the  tissue  to  be  studied — lung,  muscle,  intestine,  liver,  pancreas — 
from  a  normal  fowl  just  killed.  The  specimen  should  be  not  more 
than  J^  inch  square.  After  first  hardening  three  days  in  10  per 
cent,  formaldehyde.  Pass  through  the  following  fluids: 


1.  Alcohol,  95  per  cent 24  hours 

2.  Alcohol,  absolute 24  hours 

3.  Alcohol  and  ether,  equal  parts 24  hours 

4.  i  per  cent,  celloidin 24  hours 

5.  2  per  cent,  celloidin 24  hours 

6.  4  per  cent,  celloidin 24  hours 

7.  6  per  cent,  celloidin 24  hours] 

8.  10  per  cent,  celloidin 24  hours 

9.  Place  on  block,  and  as  soon  as  solid,  place  in  80  per  cent,  alcohol 
until  ready  to  section.     Histoloid  or  parlodion  will  take  the  place 
of  celloidin. 


348  ANATOMY   OF    THE   DOMESTIC   FOWL 

In  placing  specimen  on  the  block  be  careful  that  the  specimen  lies 
conveniently  for  cutting  the  sections  in  the  right  direction.  As  soon 
as  the  surface  has  hardened  a  little,  add  a  few  drops  of  thick  celloi- 
din,  and  repeat  until  there  is  a  good  body  of  celloidin.  Allow  to 
stand  until  the  tissues  are  quite  firmly  fastened  to  the  block,  but 
not  long  enough  to  permit  shrinking.  Then  place  in  80  per  cent, 
alcohol  until  the  specimen  is  perfectly  firm,  12  or  more  hours,  be- 
fore cutting. 

All  tissues,  cut  sections,  and  mounted  blocks  are  to  be  placed  in 
80  per  cent,  alcohol.  As  containers  for  this  purpose  shell  vials  will 
be  most  handy. 

Cut  the  sections  with  the  microtome  as  thin  as  possible,  the 
thinner  the  better.  The  following  process  of  staining  will  make  the 
nucleus  blue  and  the  cytoplasm  reddish. 

1.  Float  section  in  a  tumbler  of  tap  water. 

2.  Place  section  on  slide,  and  immerse  in  hematoxylon  for  five  to  ten  minutes. 

3.  Immerse  in  acid  alcohol  from  two  to  five  seconds. 

5.  Place  on  slide,  and  immerse  in  eosin  from  one-half  to  three  minutes. 

6.  Wash  thoroughly  in  alcohol. 

7.  Clarify  in  oil  of  cloves,  oil  of  cedar,  or  beechwood  creosote,  ten  minutes. 

8.  Mount  in  balsam. 

9.  Label  and  study. 

Delafield's  hematoxylon  is  prepared  as  follows: 

Hematoxylon  crystals 4  grams 

Alcohol,  95  per  cent 25  c.c. 

Saturated  aqueous  solution  of  ammonia  alum.   400  c.c. 

Add  the  hematoxylon  dissolved  in  the  alcohol  to  the  alum  solu- 
tion, and  expose  in  an  unstoppered  bottle  to  the  light  and  air  for 
three  or  four  days.  Filter  and  add: 

Glycerin 100  c.c. 

Alcohol,  95  per  cent 100  c.c. 

Allow  the  solution  to  stand  in  the  light  until  the  color  is  sufficiently 
dark;  then  filter,  and  keep  in  a  tightly  stoppered  bottle.  The 
solution  keeps  well  and  is  extremely  powerful.  So  long  as  it  is  good 
the  solution  has  a  purplish  tinge.  If  time  permits,  it  would  be  wise 
to  combine  the  alum,  the  hematoxylin,  and  the  water,  and  to  ripen 
the  solution  for  two  or  three  weeks  before  adding  the  other  ingredi- 
ents, which  have  a  tendency  to  prevent  oxidation. 


OUTLINE   FOR   LABORATORY    STUDY    OF    THE   CHICK         349 

The  acid  alcohol  is  made  as  follows: 

Absolute  alcohol 70  c.c. 

Distilled  water 30  c.c. 

Mix. 

Above  solution 99  c.c. 

Hydrochloric  acid i  c.c. 

Eosin  is  sold  in  two  forms,  that  soluble  in  water  and  that  soluble 
in  alcohol.  The  eosin  soluble  in  water  is  preferred,  because  with  it 
a  greater  degree  of  diffusion  in  stain  can  be  obtained. 

Keep  on  hand  a  saturated  aqueous  solution  and  dilute  with  water 
as  needed.  The  strength  of  the  solution  to  be  used  varies  somewhat 
with  the  tissue  and  the  reagent  in  which  it  is  to  be  fixed;  but  usually 
the  strength  should  be  between  J^f  o  and  ^  per  cent,  when  eosin  is 
used  after  hematoxylin.  The  diluted  solutions  should  contain  25 
per  cent,  of  alcohol,  otherwise  they  will  not  keep  well.  When  eosin 
is  used  before  an  analine  dye,  such  as  methylene  blue,  a  5  per  cent, 
or  even  a  saturated  solution  should  be  used. 

To  Stain  Sections  of  Liver  for  the  Study  of  Kupff  er  Cells.— To  bring 
out  this  reaction  Keys  suggests  the  following  technic: 

Fix  small  blocks  of  the  fresh  tissue  of  spleen  or  liver  for 
eighteen  to  twenty-four  hours  in  Miiller's  fluid  plus  5  per  cent, 
mercuric  sublimate.  Imbed  in  paraffin  and  section  to  4  microns. 
Fix  sections  to  slide,  and  stain  twenty  to  forty  minutes  with  acid 
carmine.  Wash,  and  transfer  to  equal  parts  of  a  2  per  cent, 
aqueous  solution  of  potassium  ferrocyanid  and  of  a  2  per  cent, 
aqueous  solution  of  hydrochloric  acid.  Remove  after  three  to  ten 
minutes,  wash  in  distilled  water,  and  pass  quickly  through  a  0.5 
per  cent,  aqueous  erythrosin  solution.  Dehydrate  in  alcohol,  clarify 
in  xylol,  and  mount  in  Canada  balsam. 

To  Prepare  Anatomical  Specimens  for  a  Museum. — The 
Keiserling  method  gives  the  best  results,  since  by  this  method  the 
tissues  retain  their  normal  color.  The  three  steps  are  as  follows: 

i.  Place  the  specimen  in  the  following  solution  and  leave  from 
one  to  seven  days,  the  length  of  time  depending  upon  the  size  of  the 
specimen. 

Formalin 200  c.c. 

Potassium  acetate 30  grams 

Potassium  nitrate 15  grams 

Water. . .  .  .  1000  c.c. 


35°  ANATOMY   OF   THE   DOMESTIC  FOWL 

2.  Pass  the  specimen  through  each  of  the  following  solutions, 
leaving  it  in  each  twenty-four  hours  or  until  the  normal  color  is 
obtained.    The  specimen  should  be  removed  from  alcohol  as  soon 
as  color  is  attained.     If  it  is  left  in  the  alcohol  too  long  it  will 
again  lose  some  of  its  color. 

Alcohol 40  per  cent. 

Alcohol 60  per  cent. 

Alcohol 80  per  cent. 

Alcohol full  strength 

3.  Place  the  specimen  in  the  following  permanent  solution,  label, 
and  place  in  museum. 

Glycerin 40  c.c. 

Potassium  acetate 40  grams 

Distilled  water 400  c.c. 

A  small  piece  of  thymol  must  be  placed  on  the  top  of  the  liquid 
in  each  jar,  or  mold  will  develop  and  spoil  the  specimen. 

To  Make  Specimens  Transparent. — Specimens  may  be  rendered 
transparent  by  the  method  of  Spalteholz. 

The  steps  are  essentially  as  follows: 

I.  Preparation  of  the  fresh  tissue.     If  any  parts  are  to  be  made 
conspicuous,  as  blood-vessels,  or  the  lymphatic  system,  they  must 
be  injected  with  an  insoluble,  unbleachable  substance.     Spalteholz 
recommended  carmine  or  methylene  blue,  and  carbon.     I  have 
found  Higgin's  ordinary  black  carbon  ink  excellent  for  this  purpose. 
The  system  or  systems  are  injected  with  this  substance  while  the 
tissue  is  perfectly  fresh. 

II.  Fixation.    The  tissues  are  fixed  preferably  in  10  per  cent, 
formalin.    The  length  of  time  for  fixation  depends  on  the  size  of 
the  tissue.     In  formalin  it  requires  from  eight  hours  upward  to  fix 
completely. 

III.  Rinsing.     Running  tap  water  for  five  or  ten  minutes  accom- 
plishes the  rinsing.     If  it  is  impracticable  to  pass  directly  into  the 
bleaching  fluid,  the  tissues  may  be  kept  temporarily  in  60  per  cent, 
or  70  per  cent,  alcohol.    They  should  then  be  rinsed  again  thoroughly 
in  water  when  ready  to  bleach. 

IV.  Bleaching.     The  bleaching  fluid  used  is  hydrogen  peroxid 
to  which  ammonia  is  added  until  a  white  precipitate  forms.    The 
proportion   is   approximately  two   parts   of   peroxid   and  one   of 
ammonia.     The  material  is  bleached  until  all  the  color  is  removed 


OUTLINE  FOR   LABORATORY   STUDY   OF   THE   CHICK        351 


and  the  tissue  looks  perfectly  clear  or  slightly  opaque.  It  may  be 
quite  transparent  as  the  protein  coagulate  is  somewhat  white,  but 
all  yellow  or  reddish  color  should  be  bleached  away. 

V.  Washing.     Rinse  thoroughly  in  running  tap  water  or  through 
several  changes  of  water  until  the  odor  of  ammonia  is  quite  gone. 

VI.  Dehydration.    Pass  gradually  through  alcohol  solutions,  30 
per  cent.,  50  per  cent.,  60  per  cent.,  70  per  cent.,  80  per  cent.,  95 
per  cent.,  and  last  through  absolute  alcohol.     The  time  required 
for  dehydration  will  vary  with  the  size  of  the  material,  but  in  either 
95  per  cent,  solution  or  in  absolute  alcohol  the  tissue  should  remain 
until  well  hardened,  twenty-four  hours  or  more.     Dehydration  is 
completed  by  passing  from  absolute  alcohol,  to  a  fluid  one- half 
absolute  alcohol  and  one-half  benzol;  thence  for  a  few  days  to  pure 
benzol. 

VII.  Clarifying.     From  benzol  the  material  is  finally  clarified 
in  winter-green  oil  or  any  other  standard  clearer,  and  put  up  in  its 
final  position  in  the  museum  jar. 

In  commenting  on  this  method  Dr.  A.  F.  Contant  says:  "I  have 
found  this  to  work  very  successfully  in  the  injection  of  the  lympha- 
tics of  the  human  skin,  which,  as  you  know,  is  a  rather  delicate 
injection  and  has  been  difficult  of  demonstration  by  other  methods. 
With  this  method,  however,  I  have  prepared  whole  portions,  as  the 
«ide  of  the  face,  the  leg,  etc.,  of  small  animals  and  embryos  which 
show  clearly  the  whole  course  of  the  lymphatic  vessels  and  nodes,  in 
situ,  and  their  relations  to  surrounding  parts." 

EQUIPMENT  FOR  THE  DISSECTION  LABORATORY 

Figure  84  illustrates  some  essential  equipment  for  the  dissection 
laboratory.  The  equipment  should  consist  of  a  pump,  No.  i,  which 
forces  air  through  the  rubber  tube,  No.  2,  into  the  pressure  tank,  No. 
4,  which  is  guarded  by  the  valve  at  No.  3.  At  dial,  No.  5,  indicates 
the  pressure  of  the  air  within  the  tank.  The  air  as  needed  is  re- 
leased through  an  outlet  valve.  The  air  now  passes  through  the 
rubber  tube,  No.  6,  into  the  left  arm  of  the  manometer  at  No.  7. 
The  manometer  is  simply  a  glass  tubing  filled  with  mercury  to  the 
point  indicated  at  No.  7.  By  the  side  of  the  opposite  arm  there  is 
made  a  scale  graduated  in  centimeters.  The  tube  at  No.  9  being 
attached  to  the  Y-tube,  conveys  air  under  the  same  pressure  into 
the  injection  chamber  as  that  supporting  the  column  of  mercury 


352 


ANATOMY   OF  THE  DOMESTIC  FOWL 


of  the  manometer.  It  is  necessary  to  have  a  pinch  cock,  as  indi- 
cated at  No.  n,  to  control  the  liquid  within  the  tube.  No.  12 
illustrates  the  tube  in  the  end  of  which,  No.  13,  there  is  inserted  a 


FlG.  84. — Photograph    showing    injection    apparatus,    dissection    instruments, 

dissection  pan  and  death  chamber. 

I,  Pump.  2,  Rubber  tube  leading  from  pump  to  compression  chamber.  3, 
Stop  cock.  4,  Compression  air  tank.  5,  Pressure  indicator.  6,  Rubber  tube 
leading  from  pressure  tank  to  manometer.  7,  Top  of  mercury  in  manometer 
tube.  8,  Open  end  of  glass  tube  showing  scale  in  centimeters.  9,  Tube  lead- 
ing from  4  to  injection  chamber.  10,  Injection  chamber  containing  injection 
fluid,  ii,  Pinch  cock  on  rubber  tube  connecting  injection  chamber  with  injec- 
tion canula.  12,  The  tube.  13,  Injection  canula.  14,  A  metal  dissection  tray. 
15,  Death  chamber.  16,  Base  of  same.  17,  Rubber  tube  connecting  gas  cock 
with  death  chamber.  18,  Bone  saw.  19,  Bone  cutter.  20,  Scapula.  21, 
Tenaculum.  22,  Forceps.  23,  Straight  scissors.  24,  Small  pair  of  curved 
scissors. 


trocar  which  is  introduced  into  the  artery  and  tightly  tied  with  a 
cord. 

A  convenient  dissection  tray  may  be  made  from  galvanized  iron. 
It  should  be  16  inches  square  and  about  i  inch  deep  (Fig.  84,  No.  14). 


OUTLINE  FOR  LABORATORY   STUDY   OF   THE   CHICK        353 

A  death  chamber  is  made  by  using  a  bell  jar  12  inches  in  diameter 
at  the  bottom.  This  is  used  on  a  perfectly  smooth  board  16  inches 
square.  Through  the  center  of  this  board  is  inserted  a  glass  tube 
%  inch  in  diameter.  To  this  glass  tube  is  attached  a  rubber  tube 
the  other  end  of  which  is  attached  to  a  gas  jet. 

The  instruments  needed  in  dissecting  are  illustrated  in  Fig.  84. 
No.  18  is  a  bone  saw;  No.  20  is  a  scalpel;  No.  21  is  a  tenaculum;  No. 
22  is  a  pair  of  forceps;  No.  23  is  a  pair  of  straight  scissors;  and  No.  24 
is  a  small  pair  of  curved  scissors. 

BIBLIOGRAPHY 

BAUM  AND  ELLENBERGER,  Handbuch  der  Vergleichenden  Anatomic,  Berlin, 
1912. 

BARROWS,  H.  R.,  Me.  E.  S.  Bull.  232,  pp.  16,  plates  6,  1914. 

BRADLEY,  O.  CHARNOCK,  The  Structure  of  the  Fowl,  pp.  146,  illustrations  73. 

CHAVEAU,  A.,  Comparative  Anatomy  of  Domestic  Animals,  New  York,  1893. 

CURTIS,  M.  R.,  Ligaments  of  the  Oviduct  of  the  Fowl,  Me.  E.  S.  Bull.  206,  1910. 

DUVAL,  --  ,  Atlas  of  Embryology. 

FOSTER  AND  BALFOUR,  Elements  of  Embryology. 

GADOW,  H.,  AND  SELENKA,  E.,  Vogel.  I.  Anatomischer  Theil  (Dr.  H.  G. 
Bronn's  Klassen  und  Ordnungen  des  Thier-Reichs.  Sechester  Band,  Vierte 
Ahtheiburg),  Leipsig,  1891. 

GRAY,  HENRY,  Anatomy  Descriptive  and  Surgical,  New  York,  1908. 

HEISLER,  J.  C.,  Embryology,  Philadelphia,  1901. 

KAUPP,  B.  F.,  Male  Reproductive  Organs  of  the  Fowl,  Am.  Jr.  Vet.  Med., 
vol.  x,  n,  2. 

KAUPP,  B.  F.,  Female  Reproductive  Organs  of  the  Fowl,  Am.  Vet.  Rev.,  vol. 
49,  n,  4. 

Leisering  Atlas  of  Anatomy,  edited  by  W.  ELLENBERGER,  translated  by  A.  T. 
PETERS,  Chicago,  1905. 

LILLIE,  F.  R.,  Embryology  of  the  Chick,  Chicago,  1906. 

OWEN,  R.,  Comparative  Anatomy  and  Physiology  of  Vertebrates,  London, 
1866. 

SCHMEISSER,  H.  C.,  A  Study  of  the  Blood  of  Fowls,  Johns  Hopkins  Hospital, 


SHUFELDT,  R.  W.,  Myology  of  the  Raven,  pp.  318,  illustrations  76,  London, 
1890. 

Strange  ways'  Veterinary  Anatomy,  edited  by  I.  VAUGHAN,  Edinburgh,  1892. 

SURFACE,  F.  M.,  Histology  of  the  Oviduct  of  the  Fowl,  Me.  E.  S.  Bull.,  206, 
1912. 


23 


INDEX 


ABDOMINAL  air  sac,  202 

cavity,  156 
Abducens  nerve,  270 
Abductor  minimi  digiti  muscle,  no 
Accessorius  spinalis  nerve,  274 
Accessory  organs  of  digestion,  152 
Acetabulum,  48 
Achillis  tendon,  69 
Acoustic  lamina,  323 

nerve,  306 

vesicle,  322 
Adductor  longus  muscle,  117 

magnus  muscle,  117 
Adrenal  gland,  191 
Adventitia,  201 
Afferent  nerves,  300 
Air-sacs,  199,  325 

abdominal,  202 

anterior  diaphragmatic,  202 
thoracic,  200 

cervical,  201 

femoral  extensions,  203 

humeral  extension,  200 

posterior  diaphragmatic,  202 

subpectoral  prolongation,  200 

subscapular  prolongations,  200 

suprarenal  extensions,  203 
Alae  cinereae,  291 

orbitale,  28 

temporales,  29 
Albumin,  180 

portion  of  oviduct  secreting,  185 
AUantois,  321 
Alula,  311 
Alveolar  glands,  141 

nerve,  270 
Amnion,  320,  327 
Ampullae,  306 
Ampullar  dilatations,  322 
Anapophyseal  ridge,  38 


Anatomic   specimen,    preparation    of. 

349 

Anconeus  muscle,  107 
Angiology,  206 
Angular  glands,  141 

groove,  52 

Annular  ligament,  58 
Annulus  fibrosus,  58 
Anterior  coracobrachialis  nerve,  284 

diaphragmatic  air-sac,  202 

fossa,  25 

thoracic  nerve,  284 
Aortic  arch,  325 

bulb,  324 
Aponeurosis,  59 
Apparatus,  circulatory,  206 

digestorius,  135 

respiratory,  193 

uro-genitalis,  169 

vocal,  195 

Appendages,  structure  of,  309 
Appendico-costales  muscle,  99 
Appendicular  skeleton,  13 
Apteria,  34 

Aqueduct  of  Sylvius,  268,  289 
Arachnoid,  288,  289 
Arbor  vitae,  291 
Arch,  hemal,  38 

scapular,  40 
Area  opaca,  332 

pellucida,  332 

vasculosa,  332 

Arteria  cerebri  profunda,  217 
Artery  or  arteries,  209,  325 

acromial,  222 

anterior  circumflex  humeral,  222 
vertebral,  221 

aorta,  211 

auricular,  220 

axillary,  222 


355 


356 


INDEX 


Artery  or  arteries,  basilar,  217 
brachialis,  222 

brachio-cephalic  sinister,  212 
bronchialis,  215 
carotid  trunk,  215 
carotis  cerebralis,  215 

communis,  215 

externa,  215 
.     celiac  axis,  226 
cerebral,  217 
cerebri  profunda,  217 
cervicalis  ascendens,  221 
circumflex  femoris,  228 
clavicular,  222 
coccygeal  laterales,  232 
collateralis  radialis,  223 
common  aorta,  211 
coronary,  209 
crural,  228 
esophageal,  224 
ethmoidal,  218 
ethmoidales  externa,  218 
external  facial,  2  20 

thoracic,  222 
facial,  220 
femoral  228 

hemorrhoidalis  intima,  232 
hepatica  dextra,  227 
hyoid,  218 
iliac,  229 
inferior  cerebellar,  217 

esophageal,  215 

thoracic,  222 
intercostal,  224 
internal  alveolar,  220 

ethmoid,  218 

facial,  220 

mammary,  222 

maxillary,  220 

ophthalmic,  217 

pelvic,  228 

thoracic,  222 
lacrimalis,    217 
lingualis,  220 
lumbar,  225 
median  coccygeal,  232 

hemorrhoidal,-  227 
meningeal,  216 


Artery  or  arteries,  mesenteric,  227 
muscularis,  207 
occipital,  216 
occipitalis  profunda,  216 

sublimis,  216 
ophthalmica  externa,  216 
ovarian,  226 
plexus  palpebralis,  217 

temporalis,  216 
posterior  aorta,  224 

circumflex  humeral,  223 

mesenteric,  227 

vertebral,  221 
profunda  communis,  231 

penis,  232 

pudenda  externa,  232 
pulmonalis  dexter,  213 

sinister,  213 
pulmonary,  213 
radial,  223 
ramus  anterior,  217 

posterior,  217 

profundus,  209 

superficialis,  209 
recurrent  ciliaris  posticus,  217 

ilio-celiacus,  227 

intestinalis,  227 

renalis,  229 

sinister,  227 

superior  hemorrhoidal,  227 

ulnar,  223 
renal,  226 

retinae  centralis,  217 
sacralis  media,  229,  232 
spermatic,  226 
sphenoid,  217 
spheno-maxillaris,  217 
splenic,  227 
sternaj,,  222 
sterno-clavicularis,  221 
subclavian,  212 
subcutaneous  colli,  215 
subscapular,  222 
superior  cervical,  215 

laryngeal,  218 
sylvian,  217 
temporal,  216 
thoracic,  222 


INDEX 


357 


Artery  or  arteries,  thyroid,  215 

tibialis  antica,  230 
postica,  230 

ulnar,  223 

umbilical,  228 

vertebral,  215 
Arthrology,  56 
Articulo-jugale,  58 
Arytenoid  cartilage,  194 
Atlas,  37 
Auricle,  324 
Auricular  appendage,  208 

meatus,  305 

ossicles,  305 

ventricular  valve,  207 
Axial  skeleton,  23 
Axillaris  nerve,  23 
Axis,  37 

cylinder  process,  277 
Axolemma,  277 
Axone,  277 

hill,  277 

BARBES,  310 
Barbules,  310 
Basi-branchial  bone,  35 
Basi-hyal  bone  35,  36 
Basilar  artery,  217 
Beak,  139,  310,  316 
Biceps  band,  114 

brachii,  104 

flexor  cruris,  113 
Biventer  cervicis  muscle,  77,  83 
Blastema,  322 
Blastoderm,  318 
Blood,  257 

coagulation,  260 

composition,  260 

formation,  260 

function,  257 

plasma,  260 

reaction,  257 

vascular  system,  206 

vessels,  209 
Bloom,  1 88 
Bone  or  bones.  17 

atlas,  37 

axis,  37 


Bone  or  bones,  cancellous,  18 
carpus,  44,  47 
classification,  20 
compact,  17 
composition,  21 
cervical  vertebrae,  35,  37 
coccygeal,  35,  41 
dorsal  vertebrae,  35,  39 
entoglossal,  35 
ethmoidal,  23,  27 
femur,  50 
fibula,  53 
flat,  21 

frontal,  23,  29 
furculum,  24 
growth,  20 
humerus,  44,  45 
hyoid,  35,  36 
ilium,  49 

inferior  maxilla,  23,  34 
irregular,  21 
ischium,  49 
jugale,  23,  31,  33 
lacrimal,  23,  31,  33 
long,  20 

lumbo-sacral,  35,  39 
maxillae,  23,  31,  32 
metacarpus,  44,  47 
metatarsus,  53 
nasal,  23,  31,  32 
occipital,  23,  35 
of  cranium,  23 
of  face,  31 
of  fore  limb,  44 
of  hind  limb,  50 
of  pelvis,  48 
of  shoulder,  43 
of  skull,  23 
of  thorax,  42 
of  vertebrae,  26 
palatine,  23,  31,  33 
parietal,  23,  29 
phalanges,  44,  47 
premaxilla,  23,  31 
pterygoid,  23,  31,  33 
pubis,  50 
pygostyle,  24 
quadrate,  23,  34 


358 


INDEX 


Bone   or  bones,   quadrate- jugale,   23,. 
33,  36 

radius,  44,  46 

ribs,  41 

scapular  arch,  40 

sesamoid,  54 

sphenoid,  25,  28 

supplied  with  air,  204 

tarsus,  53 

temporal,  23,  29 

tibia,  52 

turbinated,  34,  193 

ulna,  44,  46 

vomeral,  23,  31,  32 

zygomatic,  23,  31,  32 
Bowman's  capsule,  171 
Brachial  nerve  plexus,  282 
Brain,  288 

alae  cinereas,  291 

anterior  commissure,  296 

aqueduct  of  Sylvius,  289 

arbor  vitae,  291 

calamus  scriptorius,  290 

cerebral  peduncles,  291 

choroid  plexus,  296 

corpora  restiformia,  289 

corpus  callosum,  296 
striatum,  296 

coverings,  288 

crura  cerebelli,  291 
cerebri,  289 

fore,  290 

fourth  ventricle,  290 

hind,  290 

hippocampus,  297 

hypophysis,  289 

inferior  pyramids,  291 

lamina  terminales,  295 

lateral  ventricles,  297 

medulla  oblongata,  290 

mid-,  290 

nervi  amygdales,  296 

optic  chiasm,  289 
lobes,  289 

pars  commissuralis,  289 

pons  varolii,  289 

processus  cerebri  mammillares,  297 

pyramidal  columns,  291 


Brain,  sulcus  centralis,  291 

superior  pyramids,  291 

thalami  optici,  289 

tubercula  olfactoria,  297 

valve  of  Vieussens,  290 

ventricles,  lateral,  297 
Bronchi,  193,  197 

diaphragmatic,  197 
Bronchial  artery,  215 

tubes,  197 
Bronchialis  anticus,  89,  105 

longus  inferior  nerve,  284 
superior  nerve,  283 

posticus,  89 
Broncho-trachealis  anticus,  38 

brevis,  89 

Brunner's  glands,  149 
Bulla  tympaniformis,  195 
Bursa  of  Fabricius,  152 

CECA,  151 
Calamus,  310 

scriptorius,  290 

Canal  or  canals,  caroticus  et  jugulare, 
27 

Haversian,  17 

hypotarsal,  53 

ilio-lumbalis,  48 

neural,  38 

of  Petit,  305 

urinary,  170 

Volkmann's,  17 
Canaliculi,  17 
Cancelli,  17 
Capillaries,  209 
Capsular  ligament,  57 
Caput  costae,  42 
Carotid  trunk,  215 
Carotin,  314 
Carotis  cerebralis  artery,  215  . 

communis,  215 

externa  artery,  215 
Carpi  radiale,  47 

ulnare,  47 
Carpus,  44,  47 
Cartilage  semilunaris,  69 
Cavity,  cotyloid,  49 

glenoid,  44 


INDEX 


359 


Cavity,  glenoidalis  interna,  67 

nasal,  35 

sigmoid,  46 
Cavum  cranii,  23 

ilio-lumbale  dorsales,  48 
Celiac  axis,  226 
Cera,  310 

Cerate-branchial  cartilage,  35 
Cerato-glossus  muscle,  80 
Cerato-hyoideus  muscle,  80 
Cerebellar  cortex,  293 
Cerebellum,  25,  295 
Cerebral  lobes,  322 

peduncles,  291 
Cerebro-spinal  axis,  288 

nervous  system,  265 
Cerebrum,  25 
Ceroma,  37 
Cervical  air-sac,  201 

artery,  superior,  215 

nerve  ganglion,  270 

sympathetic  nerve  ganglion,  275 

vertebrae,  35,  37 
Chalazae,  180 
Chamber,  nasal,  193 
Chorion,  321,  327 
Choroid  coat,  323 
Choroidea,  303 
Chromophilic  bodies,  280 
Chromosomes,  318 
Ciliary  ganglion,  271 

nerve,  304 

process,  304,  323 
Circulatory  system,  206 
Circumconcha  muscle,  128 
Circumduction,  57 
Clavicle,  44 
Clavicular  artery,  222 
Claws,  310 

Cleido-trachealis  muscle,  75 
Cloaca,  151 
Clothing  feathers,  310 
Coccygeae  laterales  arteries,  232 

vertebrae,  35,  41 
Cochlearis,  305 
Collum  costae,  42 
Color  of  skin,  314 
Columella,  31,  305 


Column,  vertebral,  35 
Columnae  carnae,  207 
Complex  nerve  ganglion,  271 
Complexus  muscle,  81 
Composition  of  bone,  21 

of  egg,  181 
Condyle,  external,  of  femur,  50 

inner,  of  femur,  51 
Conjunctiva,  303 
Constrictions  of  Ranvier,  277 
Coprodeum,  151 
Coraco-brachialis  muscle,  103 
Coraco-humeralis  muscle,  101 
Coracoid  bone,  194 
Corium,  313 
Cornea,  323 
Corneum,  309 
Cornu,  hyoid,  35 
Coronary  artery,  209 
Corpora  restiformia,  289 
Corpus  ciliare,  303 
Costal  bronchial  tubes,  197 

process  of  sternum,  24 
Cotyloid  cavity,  65 
Course  of  food,  152 
Cranial  cavity,  23 
Cranium,  23 
Cricoid,  194 

Crico-trachealis  ligament,  194 
Cristiilii,  48 

sterni,  42 
Crop,  142 
Crura  cerebelli,  291 

cerebri,  289 
Crural  artery,  228 

nerve  plexus,  285 
Crystalline  lens,  303,  304,  305,  322, 

323 

Cuneiform  bone,  46 
Cutaneous  brachii  superior  nerve,  283 

follicle,  323 
Cutis,  313 

DEGLUTITION,  143 
Deltoid,  104 
Dendrites,  297 
Depressor  caudae  muscle,  95 
coccygis  muscle,  95 


INDEX 


Depressor  glossus  muscle,  80 

palpebrae  inferioris,  125 
Derivatives  of  germ  layer,  342 
Dermis,  313 

Dermo-cleido  dorsalis,  75 
Dermo-dorsalis,  72 
Dermo-frontalis,  72 
Dermo-humeralis,  72 
Dermo-iliacus,  75 
Dermo-pectoralis,  73 
Dermo-spinalis,  75 
Dermo-temporalis,  73 
Dermo-tensor  patagii,  72 
Dermo-ulnaris,  76 
Diaphragm,  165 

Diaphragmatic  bronchial  tubes,  197 
Diapophysis,  38 
Digastric  muscle,  78 
Digestive  apparatus,  135 
Digits,  54 
Dissection,  343 

laboratory,  351 

of  arteries,  345 

of  bone,  346 

of  muscles,  343 

of  nerves,  347 

of  viscera,  344 
Division  of  skeleton,  22 
Dorsal  ligament  of  oviduct,  188 

vertebrae,  35 

Dorso-cutaneous  nerve  plexus,  283 
Ductless  glands,  148,  329 
adrenal,  191 
parathyroid,  191 
spleen,  155 
thymus,  190 
Ductus  arteriosus,  325,  329 

Botalli,  214 
Duodenum,  148,  150 
Dura  mater,  288 

EAR  labyrinth,  305 
Ectoderm,  320 
Efferent  nerves,  300 
Egg,  180 

composition,  181 

tooth,  327 
Embryology,  318 


Endocardium,  206,  207,  208 

Endolymph,  306 

Endothelium,  206 

Entoderm,  320 

Entoglossal  bone,  35 

Ento tympanic,  77 

Epicondyloid  fossa,  52 

Epidermis,  176,  207,  313 

Epididymis,  176 

Epineural  appendage,  38 

Equipment,  351 

Erythrocytes,  258 
fate  of,  261 

Esophageal  artery,  224 
inferior,  215 

Esophagus,  142 

Esthesiology,  303 

Ethmoid  bone,  27 

Eustachian  tube,  29,  136 

Extensor     annularis     brevis    muscle, 

121 

brevis  digitorum  muscle,  120 
digitorum  communis  muscle,  106 
femoris  muscle,  113 
hallucis  brevis  muscle,  119 
indicis  longus  muscle,  108 
longus  digitorum  muscle,  119 
metacarpi  radian's  longior   muscle, 

105 

ossis  metacarpi  pollicis  muscle,  107 
proprius  pollicis  muscle,  109 

External  facial  artery,  220 
thoracic  artery,  222 

Extremitas  vertebralis,  42 

FABRICIUS,  bursa  of,  152 
Facial  artery,  220 
Falx  cerebri,  289 
Fasciculi,  70,  71 

deep,  71 

superficialis,  71 
Feathers,  311 

alula,  311 

coverts,  311 

primaries,  311 

rectrices,  311 

rudder,  41 

scapularies,  311 


INDEX 


36l 


Feathers,  secondaries,  311 

tertiaries,  311 

Female  generative  organs,  178 
Femoral  artery,  228 
Femoro-caudal,  114 
Fenestra  ovalis,  31 
rotunda,  31 
vestibularis,  105 
Fertilization,  318,  319 
Fetal  circulation,  329 
Fibers  of  Sharpey,  20 
Fibrin  ferment,  261 

formation,  261 
Fibrinogen,  261 
Fibrino-globulin,  261 
Fibular  bone,  53 

ridge,  52 
Fifth  cranial  nerve,  268 

inferior  maxillary  division,  268 
ophthalmic  division,  268 
superior  maxillary  division,  268 
Filiform  papillae,  41 
Filo-plume,  311 
Flesh,  70 

Flexor  brevis  pollicis  muscle,  109 
capitis  inferior  muscle,  82 
carpi  ulnaris  brevior  muscle,  109 

muscle,  108 
digitorum  profundus  muscle,  108 

sublimis  muscle,  108 
hallucis  brevis  muscle,  121 

longus  muscle,  122 
metacarpi  brevis  muscle,  in 

radialis  muscle,  106 
minimi  digiti  muscle,  1 10 

brevis  muscle,  no 
perforans  digitorum  profundus  mus- 
cle, 124 
perforatus    annularis    primus   pedis 

muscle,  122 

indicis  primus  pedis,  123 
medius  primus  pedis,  123 

secundus  pedis,  121,  122 
Fontanel,  27 

Foramen  intervertebralis,  39 
ischiadic,  24,  49 
magnum,  23 
Monro,  295 


Foramen  nutrient,  52 

oblongum,  24 

optic,  27 

ovale,  306,  207,  329 

pneumatic,  42,  43,  45 

triossium,  44,  6 1 
Fore  brain,  290 

limb,  44 
Fossa  anterior,  25 

articularis  transversa,  54 

cranii  media,  25 
posterior,  25 

epicondyloid,  52 

epitrochlear,  51 

intercondyloid,  51 

middle,  25 

ovalis,  207 

pneumatic,  45 

posterior,  25 

subcondyloid,  27 

trochanteric,  50 
Fourth  ventricle,  290 
Fovea  cardiaca,  324 

ischiadica,  48 

lumbalis,  48 

pudendalis,  48 
Fowl  skeleton,  21 
Frontal  bone,  29 
Function,  centers  of,  301 

muscles  of,  128 

Funnel  portion  of  oviduct,  183 
Furculum  bone,  24 

GALL  bladder,  154 
Ganglion,  300 

cardiacum,  299 

cervical,    270 
sympathetic,  275 

ciliary,  271 

complex,  271 

Gasserian,  268 

geniculate,  271 

inferior  cervical,  299 

orbito-nasal,  270 

petrosal,  272 

spheno-palatine,  270 

spinal,  276 

structure  of,  277 


362 


INDEX 


Ganglion,  superior  cervical,  299 
sympathetic,  272 

thoracic,  299 

vagi  radicis,  272 
Gastrocnemius  muscle,  117 
Gemellus  muscle,  116 
Genio-hyoideus  muscle,  79 
Genital  system,  169 
Germ  layer,  342 
Gland,  alveolar,  141 

angular,  141 

ductless,  190 

lacrimal,  303 

meibomian,  303 

mouth,  141 

mucous,  136 

oil,  41 

pharynx,  141 

sublingual,  141 

thymus,  190 

thyroid,  190 

uropygii,  309 
Glosso-hyal  element,  35 
Glottis,  194 
Gluteus  medius  muscle,  112 

minimus  muscle,  112 

primus  muscle,  112 

profundus  muscle,  112 
Gray  matte"  of  cord,  292 
Groove,  angular,  52 

tendonal,  54 
Growth  of  bone,  20 

HALLUX,  54 
Hand,  47 

Hard  palates, 136,  139 
Haversian  canals,  17 
Heart,  206 

structure  of,  207 

ventricles  of,  324 
Hemal  arch,  38 
Hemapophysis,  38 
Hemophage,  262 

Hemorrhoidalis  intima  artery,  232 
Henle's  limb,  171 

loop,  171 
Hepar,  153 
Herbst's  corpuscles,  307 


Hind  brain,  290 

limb,  50 
Hormone,  190 
Humerus,  44,  45 
Hyoid,  218 

arch,  324 

bone,  35 

Hyoideus  transversus  muscle,  80 
Hypapophysis,  38 
Hypocleidum,  24,  44, 
Hypoglossal  nerve,  274 
Hypophysis,  289,  295 
Hyporachis,  313 
Hypotarsal  canal,  53 
Hypotarsus,  53 

ILIO-LUMBALIS  dorsalis,  48 
Ilium  bone,  49 
Immovable  joints,  56 
Inferior  alveolar  artery,  220 

cerebellar  artery,  217 

larynx,  193 

maxillary  bone,  34 

pyramids,  291 

thoracic  artery,  222 

tuberculum  ossis  carpi  radialis,  47 
Infracoccygis  muscle,  96 
Infraorbital  sinus,  32 
Ingluvies,  142 
Inner  ear,  306 
Interarticulares  muscles,  85 
Intercostal  arteries,  224 

nerve,  285 

In tercos tales  muscles,  98 
Internal  adhesio  cornu  antici  cartila- 
ginis  lunatas,  67 

ethmoidal  artery,  218 

facial  artery,  220 

mammary  artery,  222 

mandibular  vein,  237 

maxillary  artery,  220 

ophthalmic  artery,  217,  218 

pelvic  artery,  228 

secretion,  190 

thoracic -artery,  222 
Interosseous  ligament,  58 
Interosseus  dorsalis  muscle,  no 

palmaris  muscle,  in 


INDEX 


363 


Interspinales  muscles,  85 
Inter transversales  muscles,  86 
Intestine,  free  portion,  150 

large,  150 

small,  147 

Intestinum  tenue,  147 
Iris,  323,  303,  304 
Ischiadic  artery,  229 

foramen,  49 

nerve,  286 
Ischium,  49 
Isthmus,  1 86 

JOINTS,  56 

immovable,  56 

mixed,  56 

movements,  56 
Jugal  bone,  23,  31,  33 
Jugular  vein,  233 

KERATO-HYALIN,  314 
Kerato-hyoideus  muscle,  80 
Kidneys,  169 

LACRIMAL  bone,  23,  31,  33 

duct,  303 

gland,  303 

sac,  303 
Lacunae,  17 
Lamellae,  17 

circumferential,  17 

concentric,  17 

interstitial,  17 
Lamina  perpendicularis,  28 
Laminae  terminale,  29 
Langerhans,  islands  of,  303 
Large  intestine,  150 
Larynx,  141 

bronchio-trachealis,  194 

false,  194 

inferior,  193 

superior,  193 

true,  194 

Lateral  process,  38 
Lateralis  caudae  muscle,  95  • 

coccygeus  muscle,  95 
Latissimus  dorsi  muscle,  96 
nerve  plexus,  282 


Leucocytes,  258 
basophile,  259 
eosinophile,  258 
lymphocyte,  259 
mast  cell,  259 
mononuclear,  259 
polymorphonuclear,  258 
Levator  caudae  muscle,  93 
coccygis  muscle,  93 
palpebrae  superioris  muscle,  124 
scapulae  muscle,  103 
Levatores  costarum  muscle,  98 
Lien,  155 

Ligament  or  ligaments,  57 
annular,  58 
annulare  radii,  61 
anterior  cruciatum  genu,  69 
anterius  ossis   carpi   metacarpi   et 

primae,  69 
phalangis  digiti  secundi,  64 

patellar,  67 
antero-inferior  humero-c  o  r  a  c  o  i  d  - 

eum,  6 1 
anticum,  69 
articulo-jugale,  58 
capsular,  57 

capsulare     atlantico-epistrophicum 
odontoideum,  59 

atlantico-occipitale,  58 

capituli  fibulae,  68 

cubiti,  61 

digitorum  pedis,  69 

obliquum,  59 

ossis  tibio-metatarsi,  69 
carpi  interosseum,  64 

radialis  internum,  64 
claviculo-sternal,  44 
coraco-furculare,  61 
coraco-humeralis,  61 
coraco-scapulare,  61 

inferius,  61 

internum,  61 
crico-trachealis,  194 
cubiti  teres,  62 
elasticum    interspinale    profundum, 

59 

superflciale,  59 
externum,  69 


364 


INDEX 


Ligament  or  ligaments,  extero-laterale 

genu,  65 

furculo-scapulare,  61 
humero-scapulare,  61 
ilio-pubic,  65 
ilio-sacrale,  65 
inferius,  61 
internum,  64 
intero-laterale  genu,  66 
interosseous,  58 
interosseum,  69 
inter  vertebral,  38 
laterale  cubiti  externum,  61 

internum,  61 
nuchae,  59 

obliquo-carpi  ulnaris,  62 
of  carpal  joint,  61 
of  ear,  58 
of  elbow  joint,  59 
of  finger,  64 
of  hip  joint,  65 
of  jaws,  58 
of  knee  joint,  65 
of  liver,  153 
of  oviduct,  1 88 
of  pelvis,  56 
of  ribs,  59 

of  shoulder  joint,  59 
of  sternum,  59 
of  tibio-metatarsal  joint,  69 
of  toes,  69 
of  vertebrae,  58 

ossis    carpi    radialis    internum    et 
metacarpi,  64 

ulnaris  externum  et  metacarpi, 

64 

internum  et  metacarpi,  64 
pollicare,  64 
popliteum,  67 

posterior  cruciatum  genu,  67 
posterius,  64 

posticum  ulnare  carpi  ulnaris,  63 
Poupartii,  65 

radiale  carpi  radialis  externum,  64 
structure,  57 
superius,  69 
suspensorium    corporum    vertebral- 

ium,  58 


Ligament  or  ligaments,  suspensorium 

dentis  epistrophei,  58 
tibio-fibulare,  68 
trans versale  commune,  67 
trans  versum,  59 
atlantis,  58,  59 
externum,  59 
triangulare,  59 
ulnare  carpi  radialis,  63 

internum,  63 
metacarpi  externum,  64 

internum,  64 
Limb,  fore,  44 

hind,  50 
Lingua,  139 
Linguales  arteries,  220 
Lipochrome,  314 
Liquor  pericardii,  207 

sanguinis,  258 
Liver,  152,  153 

ducts,  155 
Longissimus  capitis  et  atlantis,  85 

dorsi,  92 

Longus  colli  dorsalis  muscle,  83 
muscle,  83 
posticus  muscle,  83 
Lumbar  arteries,  225 
Lumbo-sacral  vertebrae,  35,  39 
Lumbo-sacrales  nerves,  285 
Lung,  195,  325 
tubules,  197,  199 
primaries,  197 
secondaries,  198 
tertiaries,  198 

Lymph  vascular  system,  206,  254 
Lymphocytes,  259 

MALARIS  muscle,  125 
Male  generative  organs,   175 
Malpighian  body,  155,  156,  171 
Mandibular  arch,  324 
Marrow,  20 

red,  20 

yellow,  20 

Masseter  muscle,  77 
Mast  cells,  259 
Maxilla,  23,  31,  32 
Maxillary  arch,  324 


INDEX 


365 


Median  coccygeal  artery,  323 

hemorrhoidal  artery,  227 

nerve,  284 
Medulla  oblongata,  25,  290 

ossium  flava,  20 

rubrum,  20 

Meibomian  glands,  303 
Melanin,  316 
Membrana  nictitans,  303,  324 

putaminae,  329 

semilunaris,  195 

testacea,  187 

tympana  interna,  195 
Membranae     obturatorae     interverte- 

brales  posteriores,  59 
Meningeal  artery,  216 
Meninges,  288 
Meniscus,  56 

inter  vertebralis,  58 
Mesentery,  156,  157 
Metacarpus,  44,  47 
Metasternum,  42 
Mid  brain,  290 
Middle  fossa  of  cranium,  25 

meningeal  artery,  217 
Molting,  313 
Motor  oculi,  267 
Mouth,  135 
Movable  joints,  56 
Mucous  glands,  136 
MUllerian  duct,  184 
Muscle  or  muscles,  70 

abductor  minimi  digiti,  no 

adductor  longus,  117 
magnus,  117 

anconeus,  107 

biceps,  104 

flexor  crurus,  113 

biventer  cervicis,  83 
maxillae,  77 

brachialis  anticus,  105 

bronchialis  anticus,  89 
posticus,  89 

broncho-trachealis  anticus,  88 
brevis,  89 
posticus,  89 

cerato-glossus,  80 

cerato-hyoideus,  80 


Muscle  or  muscles,  ciliary,  304 
cleido-trachealis,  75 
complexus,  81 
constrictor  glottidis,  87 
coraco -brachialis,  102 
coraco-humeralis,  101 
deltoid,  104 
depressor  caudae,  95 

coccygis,  95 

glossus,  80 
dermal,  70,  71 
der mo-cleido-dorsalis ,  7  5 
dermo-dorsalis,  72 
dermo-frontalis,  72 
dermo-humeralis,  72 
dermo-iliacus,  75 
dermo-osseous,  70,  73 
dermo-pectoralis,  73 
dermo-spinalis,  75 
dermo-temporalis,  73 
dermo-tensor  patagii,  72 
dermo-ulnaris,  76 
diaphragm,  90 
digastricus,  78 
ento tympanic,  77 
expansor  secundarium,  62 
extensor  digitorum  communis,  106 

femoris,  113 

indicis  longus,  108 

metacarpi  radialis  longior,  105 

ossis  metacarpi  pollicis,  107 

proprius  pollicis,  107 
femoro-caudal,  114 
flexor  brevis  pollicis,  109 

capitis  inferior,  82 

carpi  ulnaris,  108 
brevior,  109 

digitorum  sublimis,  108 

metacarpi  brevis,  in 
radialis,  106 

minimi  digiti,  no 
brevis,  no 

profundus,  108 
gastrocnemius,  117 
gemellus,  116 
genio-hyoideus,  79 
gluteus  maximus,  50 

medius,  112 


366 


INDEX 


Muscle  or  muscles,  gluteus  minimus, 
112 

primus,  112 
heart,  71 

hyoideus  transversus,  80 
infracoccygis,  96 
interarticulares,  85 
internal  obturator,  49 
interosseus  dorsalis,  no 

palmaris,  in 
interspinales,  85 
intertransversales,  86 
involuntary,  70 

striated,  71 
lateralis  caudae,  95 

coccygis,  95 
latissimus  dorsi,  96 
levator  caudae,  93 

coccygis,  93 

scapulae,  103 
levatores  costarum,  98 
longissimus  dorsi,  92 
longus  colli  anticus,  84 

posticus,  83 
masseter,  77 
mylo-hyoides,  79 
nomenclature,  71 
obliquo-transversales,  82 
obliquus  abdominis  externus,  90 
internus,  91 

colli,  83 
obturator  externus,  116 

internus  116 
of  abdomen,  90 
of  air  passage,  86 
of  anterior  pectoral  region,  99 
of  brachial  region,  104 
of  cervical  region,  81 
of  coccygeal  region,  93 
of  costal  region,  96 
of  digit,  109 

of  dorso-lumbar  region,  92 
of  forearm  and  hand,  105 
of  head,  76 
of  Inferior  larynx,  86 
of  pectoral  region,  100 
of  posterior  limb,  in 
of  scapular  region,  101 
of  sternum,  90 


Muscle  or  muscles,  of  superior  larynx, 

86 

of  tibial  region,  117 
of  tongue,  79 
pectoralis  major,  100 

secundus,  100 

tertius,  100 
peroneus  longus,  118 
platysma  myoides,  74 
pronator  brevis,  107 

longus,  107 
pterygoideus  externus,  78 

internus,  78 

lateralis,  78 

medius,  74 
rectus  abdominis,  91 

capitis  anticus  minor,  81 
lateralis,  84 
posticus  major,  82 
rhomboideus,  17 
sacro-lumbalis,  92 
sartorius,  in 
scalenus  medius,  86 
scapulo-humeralis,  101 
semimembranosus,  114 
semitendinosus,  114 

accessorius,  114 
serratus  magnus  anticus,  97 

parvus  anticus,  97 
skeletal,  70,  76 
soleus,  118 

sphincter,  pupillary,  304 
sterno-trachealis,  89 
stylo-hyoideus,  79 
subclavius,  102 
subscapularis,  103 
supraspinatus,  102 
temporal,  76 
tensor  patagii  brevis,  99 

longus,  99 
teres  et  infraspinatus,  98 

minor,  102 

thoraco-scapularis,  103 
thyreo-arytenoideus,  85 
trachelo-mastoideus,  85 
tracheo -lateralis,  87 
transversalis  abdominis,  90 
transversus  peronei,  94 
trapezius,  97 


INDEX 


367 


Muscle  or  muscles,  triceps,  104 

true  dermal,  71 

voluntary  striated,  70 
Myelon,  322 

Myeloncephalus  columns,  320 
Myocardium,  208 

NAILS,  316 

Nasal  bone,  23,  31,  32 

cavity,  35 

chambers,  193 

Naso-premaxillary  process,  324 
Nerve  or  nerves,  264 

abducens,  70 

accessorius  spinalis,  274 

acoustic,  271 

afferent,  300 

alveolar,  270 

anterior  coraco-brachialis,  284 
spinal  branches,  281 
thoracic,  284 

axillaris,  283 

brachial  plexus,  282 

brachialis  longus  inferior,  284 
superior,  283 

cells,  280 

centers,  30-1 

ciliary,  304 

cranial,  265 

crural  plexus,  285 

cutaneous     brachialis     et     inferior 

brachialis,  284 
brachii  superior,  283 

dorsal  spinal,  281 

dorsalis  plexus,  282 

dorso-cutaneous  plexus,  283 

efferent,  300 

ethmoidalis,  269 

facialis,  286 

function,  300,  301 

furcularis,  286 

glosso-pharyngeal,  272 

hypoglossal,  27,  37,  274 

intercostal,  285 

ischiadic,  49,  286 

latissimus  dorsi,  282 

lumbo-sacral,  285 

median,  284 


Nerve  or  nerves,  medullated,  277 
motor  oculi,  267 
neurolemma,  277 
nonmedullated,  277 
obturator,  286 
olfactorius,  34,  265 
optic,  267 
patheticus,  268 
peroneus  profundus,  287 
plexus  pedundus,  288 
pneumogastric,  273 
posterior  coraco-brachialis,  284 
ramus  secundus,  269 
recurrent  cardiacus,  274 

externa,  269 

hepatici,  274 

infraorbitale,  269 

laryngeus,  274 

linguales,  273 

pharyngeus,  272 

pulmonale,  274 

subcutaneous,  270 

ventralis,  281 
rhomboideus  profundus,  282 

supefficialis,  282 
scapulo-humeralis,  282 
serratus  plexus,  282 
spinal  cord,  275 
sterno-coracoideus,  284 
subcoraco-scapularis,  282 
superficialis  peroneus,  287 

serratus,  282 
supra  coracoideus,  283 
trifacial,  31,  268 
ulnar,  284 
vagus,  27,  31,  273 

group,  273 

Nerve-trunks,  structure  of,  277 
Nervous  system,  264,  300 
Neural  arch,  38 
spines,  38,  39 
Neurofibrils,  280 
Neurones,  268,  279 
Nostril,  193 
Notocord,  322 

OBLIQUE  process,  39 
Obliquo-transversales  muscle,  86 


368 


INDEX 


Obliquus  abdominis  externus  muscle, 

90 
interims  muscle,  91 

dorsalis,  125 

inferior,  127 

superior,  125 

ven tralis  muscle,    121 
Obturator  externus,  116 

internus,  116 

nerve,  286 
Occipital  artery,  215 

bone,  23,  25 

Occipitale  laterales  bone,  25 
Occipitalis  inferius  bone,  25 

profunda  artery,  215 

sublimis  artery,  215 

superioris  bone,  25 
Odontoid  process,  37 
Oil  gland,  41 
Olecranon,  46 
Olfactory  cavities,  322 

cerebral  crura,  295 

glomeruli,  265 

nerve,  265 
Oogenesis,  319 
Ophthalmic  vesicle,  322 
Ophthalmica  externa,  216 
Optic  chiasm,  289 

lobes,  322,  389 

nerve,  267 
Orbicularis  oculi,  124 

palpebrarum  muscle,  124 
Orbit,  323 
Orbital  process,    30 
Orbito-nasal  ganglion,  270 
Organ  of  hearing,  304,  322 

of  sight,  303 

of  smell,  307 

of  taste,  307 

of  touch,  307 
Os  angulare,  30 

articulare,  30 

transversale,  105 
Osseous  structure,  17 

tissue,  17 

Ostium  tubae  abdominale,  183 
Otocrane,  323 
Otoliths,  322 


Ovarian  artery,  226 

pocket,  189 
Ovary,  325 
Oviduct,  182,  325 
Ovum,  318 

PALATAL  papillaries,  141 
Palatine  glands,  141 
Palatinus  bone,  23,  31,  33 
Palatum  durum,  139 
Palpebral  plexus,  217 
Pancreas,  152,  155 
Papilla,  141 
Parapophysis,  38 
Parietal  bone,  29 
Pars  commissuralis,  289 

glandularis,  143 

muscularis,  143 

renalis,  251 

Partes  pedunculares,  294 
PateUa,  53 
Patheticus,  268 
Pecten,  303,  323 
Pectoralis  major,  100 

secundus,  100 

tertius,  101 
Pelvic  cavity,  156 

girdle,  48 
Pericardium,  207 
Perimysium,  70 
Periosteum,  18 
Peritoneum,  156 
Peroneus  longus,  118 

nerve,  287 
Pessulus,    195 
Petrosal  ganglion,  272 
Phalanges,  44,  47,  54 
Pharynx,  54,  141 
Pia  mater,  288 
Pineal  gland,  295 
Pituitary  body,  25,  289,  295 
Placenta,  321 
Planum  coccygeum,  48 
Plasma,  261 

Platysma  myoides  muscle,  74 
Pleurapophysis,  38 
Plexus,  abdominal,  299 

anterior  splanchnic,  300 


INDEX 


Plexus,  lacrimal,  217 

mesenteric,  299 

muscularis,  217 

pedundus,  288 

posterior  splanchnic,  300 

thoracic,  299 
Plica  primitivse,  320 
Pneumatic  foramen,  42,  43,  45 
Pons  varolii,  289 
Post-acetabular  ridge,  48 
Posterior  aorta,  224 

circumflex  artery,  223 

diaphragmatic  air  sac,  202 

fossa,  25 

nares,  136 

orbitalis,  30 

vena  cava,  247 

vertebral  artery,  221 

vein,  234 

Poupart's   ligament,    65 
Prezygapophyses,  39 
Primaries,  311 
Primitive  streak,  321 
Process,  costal,  43 

lateral,  37,  39 

oblique,  37,  39 
of  sternum,  42 

odontoid,  37 

xiphoid,  43 
Processus  acusticus  externus,  31 

ciliaris,  304 

coracoideus,  44 

cubitalis  humeri,  45 

frontalis,  32 
anterior,  32 
posterior,  32 

furcularis,  43 

humeralis,  43 

intermaxillaris,  32 

ischiadicus,  49 

maxillaris,  32 
anterior,  32 

odontoid,  37 

olecranalis  coracoideus,  46 

orbicularis,  28,  29 

orbitalis,  29 

palatinus,  32 

posterior  orbitalis,  30 


Processus  uncinatus,  24 

zygoma ticus,  28,  30 
Profunda  penis,  232 
Pronation,  57 
Pronator  brevis  muscle,  107 

longus,  107 
Proteids  of  plasma,  261 

of  serum,  261 
Proventriculus,  143 
Pro  vertebra,  320 
Pterygoideus  externus  muscle,  78 

internus  muscle,  78 

lateralis  muscle,  78 

medialis  muscle,  78 
Pterylae,  311 
Pubis,  50 

Pudenda  externa  artery,  232 
Pulmonalis  dextra,  213 

sinistra,  213 
Pulmonary  artery,  213 
vein,  233 
Pulp,  311 

Punctum  saliens,  320 
Purkinje  cells,  293 
Pyramidal  columns,  291 

QUADRATE,  34 
Quadrato-jugale,  23,  31,  33 
Quadratus  nictitans,  125 
QuiU,  310 
feathers,  310 

RACHIS,  310,  313 
Radial  artery,  223 
Radius,  44,  46 
Rami  communicantes,  276 

glottis,  194 
Ramus  ascendens  ossis  ischii,  49 

ciliaris  posticus,  217 

posterior  artery,  217 

profundus  artery,  209 

superficialis  artery,  209 
Rectrices,  41,  311 
Rectus  abdominalis  muscle,  91 

capitis  an  ticus  minor  muscle,  81 
dorsalis  major  muscle,  82 
posticus  major  muscle,  82 


370 


INDEX 


Rectus  capitis  ventralis  muscle,  82 

dorsalis  muscle,  127 

externus  muscle,  127 

inferior  muscle,  127 

interims  muscle,  128 

lateralis  muscle,  127 

medialis  muscle,  128 

superior  muscle,  127 
•  ventralis  muscle,  127 
Recurrent  cardiacus  nerve,  274 

hepatici  nerve,  274 

infraorbital  nerve,  269 

intestinalis  nerve,  227 

laryngeus  nerve,  273 

lingualis  nerve,  273 

pharyngeus  nerve,  272 

pulmonale  nerve,  274 

renal  artery,  223 

renales  nerves,  229 

sinister  artery,  227 

subcutaneous  nerve,  270 
Red  blood  cells,  258 
shape,  258 
size,  259 
structure,   259 
Reflex  action,  301 
Renal  artery,  226 

corpuscle,  171 
Respiratory  apparatus,  193 
Rete  malpighii,  313 
Retina,  303,  304,  323 
Rhomboideus  muscle,  97 

profundus  nerve,  282 

superficialis  nerve,  282 
Ribs,  41 

false,  41 

true,  41 
Ridge,  ectonemial,  52 

fibrillar,  52 

post-acetabular,  48 

procnemial,  52 

trochanteric,  50 
Rotation,  57 
Round  ligament,  65 
Rudder  feathers,  41 

SACRALIS  media  artery,  229,  232 
Sacro-lumbalis  muscle,  92 


Sacs,  air,  199 
Sarcolemma,  70 
Sartorius  muscle,  in 
Scala  tympani,  306 

vestibuli,  306 
Scalenus  medius  muscle,  86 

muscle,  86 

Scapho-lunar  bone,  47 
Scapula,  43 
Scapulo-humeralis  muscle,  101 

nerve  plexus,  282 
Sclerotic  coat,  303,  304 
Secondaries,  311 
Secretion,  internal,  190 
Semilunar  cartilage,  67 
Semimembranosus  muscle,  114 
Seminiferous  tubules,  318 
Semitendinosus  muscle,  114 

accessorius  muscle,  114 
Sense  of  hearing,  305 

of  sight,  303 

of  smell,  307 

of  taste,  307 

of  touch,  307 

organ,  303 
Sensory  nerves,  300 
Septum  nasi,  33 
Serous  cavity,  156 

membrane,  156 

sac,  156 
Serratus  magnus  anticus  muscle,  97 

nerve  plexus,  282 

parvus  anticus  muscle,  97 
Serum,  261 

albumin,  261 

globulin,  261 
Sesamoid  bone,  54 
Sharpey's  fibers,  20 
Sheath  of  Schwann,  277 
Shell  bloom,  188 

gland,  187 

membrane,  181 

structure,  181 

tint,  181 

Shoulder  girdle,  43 
Sinus  foraminis  occipitales,  240 

foveae  hemispherii  cerebelli,  241 

infraorbitalis,  32 


INDEX 


371 


Sinus  longitudinalis,  239 

occipitalis,  240 
externus,  240 

petrosus  sphenoideus,  240 

rhomboideus,  276 

semicircularis,  240 

temporales,  332 

temporo-sphenoideus,  240 

transversus,  240 

venosus  annularis  basilaris,  240 
Skeleton,  21,  24 

appendicular,  43 

axial,  22 

division,  22 
Skin,  309,  323 
Small  intestine,  147 
Smooth  muscle,  70 
Soleus  muscle,  118 
Somatic  cell,  318 
Spermatic  artery,  226 
Spermatids,  318 
Spermatocyte,  318 
Spermatogenesis,  318 
Spermatogonia,  318 
Spermatozoa,  176,  318 
Sphenoid  artery,  217 

bone,  28 

rostrum,  29 

Spheno-maxillary   artery,    217 
Spheno-palatine  nerve  ganglion,  270 
Spinal  cord,  38 

nerves,  281 

nervous  system,  264 
Splanchnology,  135 
Splanchnopleure,  327 
Spleen,  152,  155 
Splenic  artery,  227 

capsule,  155 

Pulp,  155 
Spur,  54,  317 

Squamous  epithelium,  137 
Sternal  artery,  222 
S  te  rno-cla vicularis  artery,    221 

muscle,  284 

Sterno-coracoideus  nerve,  284 
Sterno-hyoideus  muscle,  80 
Sterno-trachealis  muscle,  89 
Sternum,  42 


Stigmen,  179 
Stomach,  143 
Stratum  corneum,  141,  313,  314 

germinativum,  314 

granulosum,  314 

lucidum,  344 

Malpighii,  314 
Stylo-hyoideus  muscle,  79 
Styloid  process  of  ulna,  46 
Subclavian  artery,  234 
Subcondyloid  fossa,  27 
Subcoraco-scapularis  nerve,  282 
Subcutis,  309 
Subscapularis  artery,  222 
Succus  entericus,  152 
Sulcus  ilio-lumbalis  dorsalis,  48 

centralis,  291,  294 

longitudinalis,  291 
Superficialis  peroneus  nerve,  287 

serratus  nerve,  282 
Superior  laryngeal  artery,  218 

larynx,  193 

median  fissure  of  cord,  276 

pyramidalis,  291 

sympathetic  ganglion,  272 

tuberculum  ossis  carpi  radialis,  47 
Supra-coracoideus  nerve,  283 
Sylvian  artery,  217 

Sympathetic      caroticus      cephalicus, 
298 

nervous  system,  264,  297 

ophthalmic  plexus,  298 

recurrent  cardiacus,  299 

temporo-lacrimalis,  298 

thoracic  trunk,  299 
Symphysis  ilio-sacralis,  49 

ilio-sacri,  49 
Synovial  apparatus,  57,  156 


METATARSUS,  53 

Tears,  303 

Temporal  arterial  plexus,  216 

artery,  215 
.  bone,  29 

petrosal  portion,  31 
squamous  portion,  30 
Temporalis  muscle,  76 
Tendon  Achillis,  69 


372 


INDEX 


Tendonal  groove,  54 
Tensor  patagii  brevis,  99 
longus,  99 

tympani,  128 
Teres  et  infraspinatus  muscle,  98 

minor  muscle,  103 
Testicles,  175 
Thalamus  optici,  289 
Thorax,  41 
Thymus  gland,  190 
Thyroid  artery,  215 

gland,  190 

Tibialis  an ticus  muscle,    119 
Tissue,  osseous,  17 
Toes,  54 

Tongue,  139,  140 
Touch  corpuscle,  307 
Trachea,  194 

Trachelo-mastoideus  muscle,  85 
Transparent  specimens,  350 
Transversalis  abdominis  muscle,  92 
Transverse  fissure,  289 

vein,  233 

Transversus  peronei,  94 
Trapezius  muscle,  97 
Triangularis  sterni  muscle,  90 
Triceps  brachii,  104 

muscle,  104 
Trifacial  nerve,  268 
Trochanter,  50 
Trochanteric  fossa,  50 

ridge,  50 

Trochlea,  femoral,  50 
True  joints,  56 
Tuba  auditiva,  29,  136 
Tuber    cinereum    et     infundibulum, 

289 

Tuberculum  costae,  42 
Tuberositas  furcularis,  44 

humeralis,  44 

muscularis,  64 

radii,  46 

scapularis,  44 
Tubuli  seminiferi,  176,  318 

uriniferi  corticalis,  170 
Tunica  adventitia,  210 

intima,  210 

media,  210 


Turbinate  bones,  34,  193 
Tympanic  membrane,  31 

ULNA,  44,  46 
Ulnar  nerve,  284 
Umbilical  artery,  228 
Umbilicus,  31 
Ureter,  174,  187 
Urinary  apparatus,  169 

canals,  170 
Urodeum,  151 
Urogenital  system,  169 
Urohyal  process,  35 

VAGINA,  187 

Valve  of  Vieussens,  290 

Valves  of  veins,  211 

Vane,  310 

Vas  deferens,  175,  178 

Vasa  vasorum,  211 

Vastus  externus  muscle,  113 

internus  muscle,  113 
Vaxillum,  310 
Vein  or  veins,  233 

anterior  vertebral,  234 

ascendentes  laterales,  242 

basilica,  246 

brachialis,  246 

carotes,  241 

cava  sinister,  245 

cavae,  233 

cephalica  posterior,  239 

coccygea,  250 

colH  cutineae,  242 

coracoidea,  244 

cutinea  abdominis  femoralis,  250 
caudalis,  251 
cruralis,  249 
pubica,  251 

epigastric,  250 

esophageal,  243 

facialis  communis,  238 
cutinea,  238 
externa,  235 

femoralis  anterior,  250 
interna  profunda,  250 

foraminis  occipitalis,  240 

fovae  hemispherii  cerebelli,  241 

glandularum  thyroidearum.  243 


INDEX 


373 


Vein  or  veins,  humeri,  245 
hypogastric,  251 
intercostales,  244 
internal  mandibular,  237 
intervertebrales  lumbalis,  252 

sacrales,  249 
ischiadic,  252 
jugularis,  233 
linguales,  242 
lingualis  et  hyoides,  238 
longitudinalis,  239 
maxillaris,  235 

metatarsalis  dorsalis  interna,  249 
profunda,  249 

externa,  249 

plantaris  profunda,  249 
occipitalis,  240 

externa,  242 

externus,  240 
of  brain  cavity,  241 
of  dorsal  region,  243 
of  fore  limb,  245 
of  head,  235 
of  hind  limb,  248 
of  neck,  242 
of  thorax,  244 
of  viscera,  252 
ophthalmica,  236 
ovariana,  252 
palpebralis,  238 
petrosus  sphenoideus,  240 
pharyngeae  superiores,  238 
poplitealis,  251 
posterior  vena  cava,  247 

vertebral,  234 
profundus  ulnaris,  245 
proventricularis  communis,  245 

inferior,  253 
pudenda,  251 
pulmonary,  233 
radialis  profunda,  245 
renales,  249 
renalis  magna,  252 
retis  mirabilis  temporalis,  237 
sacrales,  249 
semicircularis,  240 
spermatica,  251 
sternalis,  244 


Vein  or  veins,  structure  of,  211 

subclavicularis,  233 

subscapularis,  243 

suprapalatina,  236 

suprarenalis  externa,  251 
revehentes,  252 

surales,  244 

temporalis,  238 

temporo-sphenoideus,  240 

testiculas.  252 

thoracica  externa,  244 
interna,  244 

tibialis  postica,  248 

trachealis,  243 

transversus,  233,  238 

vertebralis  lateralis  dorsalis,  243 
Venous  sinuses,  239 

trunks,  233 

Ventral  ligament  of  oviduct,  188 
Ventricles  of  heart,  324 
Ventriculus,  143 
Vertebrae,  35 

cervical,  35 

coccygeal,  35 

dorsal,  35,  39 

lumbo-sacral,  35,  39 
Vertebral  artery,  215 

column,  35 
Vestibulum,  306 
Vffli,  149 
Vitellicle,  321 
Vitelline  membrane,  180 

veins,  324,  327 
Vocal  apparatus,  195 

WISH  bone,  244 
Wolffian  duct,  184,  339 

XANTHOPHYLL,  314 

YOLK,  1 80 
sac,  327 

ZONA  opaca,  320 

pellucida,  320 
Zygapophyses,  38,  39 
Zygomatic  bone,  23,  31,  33 

process,  30 


Books  for  Veterinarians 

Published  by 

W.  B.    SAUNDERS   COMPANY 

West  Washington  Square  Philadelphia 

London:  9,  Henrietta  Street,  Covent  Garden 
Second  Edition  published  September,  1914 

Sisson's  Anatomy  of  Domestic  Animals 

Anatomy  of  Domestic  Animals.  By  SEPTIMUS  SISSON,  S.  B.,  V.  S., 
Professor  of  Comparative  Anatomy,  Ohio  State  University.  Octavo 
of  930  pages,  725  illustrations.  Cloth,  $7.50  net. 

Here  is  a  work  of  the  greatest  usefulness  in  the  study  and  pursuit  of  the  veter- 
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of  the  principal  domesticated  animals — an  exhaustive  gross  anatomy  of  the 
horse,  ox,  pig,  and  dog,  including  splanchnology  of  the  sheep. 

Sesco  Stewart,  M.  D.,  D.  V.  M.,  Kansas  City  Veterinary  College:  "I 
believe  Sisson's  Anatomy  is  the  best  text-book  on  anatomy  that  we  have  in 
English,  and  I  advise  our  students  to  buy  nothing  else." 

Hadley  on  the  Horse  A*£X 

The  Horse  in  Health  and  Disease.  By  FREDERICK  B.  HADLEY,  D.  V.  M., 
Associate  Professor  of  Veterinary  Science,  University  of  Wisconsin. 
12mo  of  260  pages,  illustrated.  Cloth,  $1.50  net. 

This  new  work  correlates  the  structure  and  function  of  each  organ  of  the  body, 
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especially  as  an  introductory  text  to  the  study  of  veterinary  science. 

David  S.  White,  E>.  V.  M.,  College  of  Veterinary  Medicine,  Ohio  State 
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Saunders'  Books  for  Veterinarians 


Kaupp's  Poultry  Culture 

Poultry  Culture,  Sanitation,  and  Hygiene.  By  B.  F.  KAUPP,  M.  S., 
D.  V.  MM  Poultry  Investigator  and  Pathologist,  North  Carolina  Experi- 
ment Station.  12mo  of  418  pages,  with  197  illustrations.  Cloth, 
$2.00  net.  Published  September,  1916. 

This  work  gives  breeds  and  varieties  of  poultry,  hygiene  and  sanitation, 
ventilation,  poultry-house  construction,  equipment,  ridding  stock  of  vermin, 
internal  parasites,  and  other  diseases.  Other  important  subjects  are  gross 
anatomy,  functions  of  the  digestive  organs,  food-stuffs,  fattening,  dressing, 
packing,  caponizing,  etc.,  etc. 

O.  L.  Eckman,  New  Hampshire  Agricultural  and  Mechanical  College:  "I 
am  glad  to  say  that  I  think  it  is  a  very  good  volume,  and  I  shall  be  glad  to 
recommend  it  to  students." 

Lynch's  Diseases  of  Swine 

Diseases  of  Swine.  With  Particular  Reference  to  Hog-cholera.  By 
CHARLES  F.  LYNCH,  M.  D.,  D.  V.  S.,  Terre  Haute  Veterinary  College. 
With  a  chapter  on  Castration  and  Spaying,  by  George  R.  White,  M.  D., 
D.  V.  S.,  Tennessee.  Octavo  of  741  pages,  illustrated.  Cloth,  $5.00 
net.  Published  November,  1914- 

Dr.  Lynch's  book  devotes  80  pages  to  the  different  breeds,  giving  valuable 
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more  than  400  pages  on  hog-cholera,  giving  history,  causes,  pathology,  types, 
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swine. 

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diseases." 


Sharp's  Veterinary  Ophthalmology 

Ophthalmology  for  Veterinarians.  By  WALTER  N.  SHARP,  M.  D., 
Professor  of  Ophthalmology,  Indiana  Veterinary  College.  12mo  of  210 
pages,  illustrated.  Published  April,  1913.  Cloth,  $2.00  net. 


This  book  takes  up  a  much-neglected  subject  in  veterinary  medicine.  The 
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refraction,  and  medicines  used  in  ophthalmologic  treatment. 

Dr.  John  \V.  Adams,  University  of  Pennsylvania  School  of  Veterinary 
Medicine:  "It  is  reliable,  practical,  sufficiently  complete,  and  well  suited  to 
the  needs  of  students  of  veterinary  medicine." 


Saunders'  Books  for  Veterinarians 


Buchanan  and  Murray's  Bacteriology 

Veterinary    Bacteriology.      By  ROBERT  E.  BUCHANAN,    PH     D.,  and 
CHARLES  MURRAY,  B.  Sc.,  D.  V.  M.,  Iowa  State  College  of  Agricul- 
ture   and    Mechanic    Arts.     Octavo  of  590  pages,  209  illustrations. 
Cloth,  $3.50  net.     Second  Edition  published  September,  1916. 

Professor  Buchanan's  new  book  expresses  the  most  advanced  knowledge  on 
this  subject.  Some  important  subjects  discussed  are  immunity,  antiseptics, 
culture  media,  isolation  of  cultures,  manufacture  of  the  various  toxins,  anti- 
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B.  F.  Kaupp,  M.  S.,  D.  V.  M.,  North  Carolina  Agricultural  College,  West 
Raleigh:  "It  is  the  best  in  print  on  the  subject.  What  pleases  me  most  is  that 
it  contains  all  the  late  results  of  research." 

Prentiss'  Embryology      . 

Laboratory  Manual  and  Text-book  of  Embryology.  By  CHARLES  W. 
FRENTISS,  A.  M.,  PH.  D.,  formerly  Professor  of  Microscopic  Anatomy 
in  the  Northwestern  University  Medical  School,  Chicago.  Octavo  of 
400  pages,  3G8  illustrations,  many  in  colors.  Cloth,  $3.75  net. 

This  new  work  on  Embryology  is  both  laboratory  manual  and  text-book.  A 
large  number  of  chick,  pig,  and  human  embryos  are  described,  giving  clear, 
definite  directions  for  making  dissections.  There  are  368  practical  illustra- 
tions, nearly  40  of  them  in  colors. 

Dr.  J.  W.  Papez,  Atlanta  Medical  College:  "It  is  the  only  book  that  has 
fulfilled  my  needs  exactly.  I  am  using  the  book  this  session  and  will  continue 
to  use  it  in  the  future." 

'  o,      U-I  o,  -t-  ^1  ^  Third  Edition 

S     rllStOlOgy  Published  August,  1914 

Normal  Histology  and  Organography.  By  CHARLES  HILL,  M.  D.  12mo 
of  483  pages,  337  illustrations.  Cloth,  $2.25  net. 

Dr.  Hill's  work  is  characterized  by  a  brevity  of  style,  yet  a  completeness  of 
discussion  rarely  met  with  in  a  book  of  this  size.  The  entire  field  is  covered, 
beginning  with  the  preparation  of  material,  the  cell,  the  various  tissues,  on 
through  the  different  organs  and  regions,  and  ending  with  fixing  and  staining 
solutions. 

E.  I).  Ball,  Utah  Agricultural  Experiment  Station :  "Dr.  Hill's  work  is  by  far 
the  best  one  for  agricultural  students  that  I  have  ever  examined." 


Saunders'  Books  for  Veterinarians 


Published  July,  1917 

Dietrich's  Live  Stock  on  the  Farm 

Live  Stock  on  the  Farm.  By  WILLIAM  DIETRICH,  PH.  D.,  Department 
of  Agriculture,  University  of  Minnesota.  12mo  of  275  pages,  illus- 
trated. 

This  work  takes  up  the  entire  question  of  the  care  of  all  kinds  of  live  stock — 
horses,  the  dairy  cow,  beef  cattle,  sheep,  swine,  poultry  of  all  kinds.  There 
is  a  large  section  on  feeding,  which  gives  you  the  amount  of  each  kind  of  food 
for  market  pigs,  calculating  rations,  method  of  feeding,  etc.;  another  on 
breeding  for  special  uses,  castration,  tuberculin  test,  cholera  vaccination,  the 
Babcock  test.  etc.  It  is  a  clear  presentation  of  economic  live  stock  raising 
based  on  sound  scientific  principles.  The  text  is  fully  illustrated.  The  book 
is  written  to  give  information  to  farmers  generally,  to  all  those  interested  in 
live  stock  raising  and  breeding,  and  especially  as  a  text-book  for  agricul- 
tural schools,  high  schools,  and  colleges. 

Ready  September,  1917 

Kaupp's  Anatomy  of  the  Fowl 

Anatomy  of  the  Fowl.  By  B.  F.  KAUPP,  M.  S.,  D.  V.  M.,  Poultry  In- 
vestigator and  Pathologist,  North  Carolina  Experiment  Station.  12mo 
of  400  pages,  illustrated. 

You  have  here  a  systematic  text-book  based  on  laboratory  studies.  The 
work  takes  up  osteology,  the  articulations,  the  musculature,  the  viscera,  the 
veins,  arteries  and  lymphatics,  neurology,  the  special  senses.  There  is  a 
chapter  on  embryology  and  on  the  methods  of  preparing  specimens.  Dr. 
Kaupp's  mastery  of  the  subject  is  absolute,  and  his  treatment  of  it  here  is 
scholarly  and  authoritative.  The  work  is  profusely  illustrated. 

Arey's  Laboratory  Histology 

A  Laboratory  Guide  in  Histology.  By  LESLIE  B.  AREY,  M.  D.,  As- 
sociate Professor  of  Microscopic  Anatomy,  Northwestern  University 
Medical  School.  12mo  of  125  pages.  Published  July,  1917. 

This  book  is  adaptable  for  use  in  any  standard  course  of  normal  histology. 
The  treatment  of  the  subject  throughout  is  on  an  induction  basis,  the  student 
being  led  to  scrutinize,  explain,  and  reach  independent  conclusions.  The  fre- 
quent interjection  of  appropriate  queries  relieves  the  instructor  of  much 
tedious  and  often  belated  individual  quizzing  and  directing.  The  inter- 
relations and  significance  of  fundamental  tissues  and  microscopic  anatomy 
are  emphasized. 


14  DAY  USE 

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